{"gene":"TG_227280","gene_symbol":"GRA3","run_date":"2026-09-05T22:31:42","timeline":{"discoveries":[{"year":1994,"finding":"GRA3 is stored as a soluble protein in dense granules and, following secretion into the parasitophorous vacuole, inserts directly into the vacuole membrane in an oligomeric form via hydrophobic interactions; it cannot be removed by sodium carbonate extraction, is not labeled by [1-14C]acetate, and cross-links to itself (forming a ladder on SDS-PAGE) but no other parasite or host proteins co-precipitate with cross-linked GRA3.","method":"Sucrose flotation gradients, Triton X-114 phase partitioning, sodium carbonate extraction, chemical cross-linking, SDS-PAGE, [1-14C]acetate labeling","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — multiple orthogonal biochemical methods in a single rigorous study establishing mechanism of membrane insertion","pmids":["8195173"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":1994,"finding":"GRA3 cDNA encodes a 30 kDa protein with an N-terminal signal sequence (sufficient to target GFP to dense granules and PV) and four short hydrophobic regions insufficient to span the membrane; Southern blot indicates a single-copy gene; GRA3 localizes to dense granules, the PVM, and PVM extensions protruding into the host cytoplasm.","method":"cDNA cloning, Northern blot, Southern blot, in vitro translation with dog pancreas microsomes, immunofluorescence, immunoblot with affinity-purified antibodies","journal":"Molecular and biochemical parasitology","confidence":"High","confidence_rationale":"Tier 1 / Strong — multiple orthogonal molecular methods; signal peptide function confirmed by in vitro translation with microsomes","pmids":["7739670"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":1993,"finding":"Dense granule exocytosis (releasing GRA2 and GRA3) occurs in the apical area of the tachyzoite within minutes of invasion; dense granule contents appear first as dense material between parasite and vacuole membranes before the vacuolar network or PVM are immunolabeled; GRA3 antibodies label the PVM and strands extending from PVs into the host-cell cytoplasm.","method":"Immunofluorescence assay (IFA), immunoelectron microscopy, serial sectioning, freeze-fracture studies at defined post-invasion time points","journal":"Parasitology research","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple imaging modalities with temporal resolution; replicated in same study by independent methods","pmids":["8415546"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":1999,"finding":"GRA3 release from dense granules is constitutive and calcium-independent; the NSF/SNAP/SNARE/Rab machinery mediates dense granule exocytosis, as shown by inhibition with N-ethylmaleimide and Rab-GDI, and augmentation with recombinant NSF and α-SNAP in streptolysin O-permeabilized parasites.","method":"Endogenous GRA3 secretion assay in intact and SLO-permeabilized parasites, recombinant protein addition, pharmacological inhibitors (NEM, Rab-GDI), GTPγS and cAMP treatments","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstitution with recombinant components plus pharmacological inhibitors in permeabilized parasite system, multiple orthogonal interventions","pmids":["9891012"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2005,"finding":"The originally published GRA3 sequence is an artificial chimera of two proteins. The authentic GRA3 (24 kDa, recognized by mAb 2H11) contains an N-terminal secretory signal sequence and a transmembrane domain consistent with PVM insertion, plus a C-terminal dilysine (KKXX) ER retrieval motif. The signal peptide alone is necessary and sufficient to target GFP to dense granules and the PV. A Neospora caninum homologue was identified.","method":"Sequence analysis, recombinant antibody production, immunoblot of ESA, GFP fusion/targeting assay, bioinformatics identification of KKXX motif","journal":"Parasitology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — sequence correction validated by antibody recognition of correct MW protein plus GFP targeting experiment; single lab but multiple orthogonal methods","pmids":["16149193"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2007,"finding":"Within the parasite and the PV soluble fraction, GRA2 and GRA5 form high-molecular-weight oligomeric complexes with multiple GRA proteins; affinity purification of HA-FLAG-tagged GRA2 from ΔeGRA2 complemented parasites co-purified GRA3, GRA6, and GRA7 as the major partners. After membrane insertion, GRA2 associates with GRA5 and GRA7 but not GRA3.","method":"Affinity chromatography (HA-FLAG tag), conventional chromatography, complementation of KO parasites with tagged proteins, co-purification/MS","journal":"Molecular and biochemical parasitology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal affinity purification from complemented KO parasites with MS identification; single lab, multiple orthogonal approaches","pmids":["17959262"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2007,"finding":"Targeted deletion of GRA3 in a type II strain shows no effect on cell culture growth rate or bradyzoite formation, and does not alter localization of other dense granule proteins or association with host cell organelles; however, at ~4× the LD50, ΔeGRA3 mice survived acute infection, and complementation restored and even enhanced virulence, demonstrating GRA3 contributes to acute virulence in vivo.","method":"Homologous recombination gene knockout, plaque assay, bradyzoite differentiation assay, IFA for GRA protein localization, mouse survival experiments, genetic complementation","journal":"Molecular and biochemical parasitology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — clean KO with complementation rescue in mouse virulence model; multiple cellular phenotypes tested; single lab","pmids":["17418907"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":"type II"}]},{"year":2008,"finding":"PVM-inserted GRA3 physically interacts with CAMLG (calcium modulating ligand), a type II transmembrane protein of the host cell ER, as established by yeast two-hybrid screening of a HeLa cDNA library, GST pull-down, and co-immunoprecipitation; GRA3 and CAMLG co-localize at the PVM in infected cells, suggesting GRA3 mediates ER recruitment to the PVM.","method":"Yeast two-hybrid (GRA3 ORF vs HeLa cDNA library), GST pull-down assay, co-immunoprecipitation, co-transfection/co-localization by fluorescence microscopy, IFA in infected cells","journal":"The Korean journal of parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — three orthogonal binding assays (Y2H, GST pull-down, Co-IP) plus co-localization; single lab","pmids":["19127325"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2008,"finding":"GRA7 strands in the host cytosol (formed within 10 min of invasion) also contain GRA1 and GRA3, indicating GRA3 is present in cytosolic strand-like structures alongside rhoptry proteins ROP2 and ROP4 in infected host cells.","method":"IFA with co-labeling of GRA7, GRA1, GRA3, ROP2, ROP4 at defined post-invasion time points","journal":"Infection and immunity","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — single co-localization study; co-labeling in fixed cells; independently observed for multiple proteins","pmids":["18809661"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":1995,"finding":"Sporozoites of T. gondii lack GRA3 protein (not detected by IFA or Western blot in sporozoite-infected cells 2–15 h post-inoculation); GRA3 expression first appears 15 h post-inoculation and is present in all intracellular parasites at 24 h, coinciding with expression of the tachyzoite marker SAG1 and onset of replication.","method":"Indirect immunofluorescence, Western blot of sporozoite extracts, time-course monitoring of GRA3 and SAG1 expression","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — IFA and Western blot with temporal resolution; negative result rigorously established in sporozoites","pmids":["8720177"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2019,"finding":"Deletion of PVM-associated GRA3 in the type II Prugniaud strain induced severe defects in chronic cyst development in vivo without affecting parasite growth rate or in vitro cyst differentiation; acute virulence of PruΔgra3 was reduced but not abolished.","method":"Targeted gene deletion (Δgra3) in type II Pru strain, in vivo mouse cyst burden assay, in vitro bradyzoite differentiation, plaque assay","journal":"mBio","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO in low-virulence strain with both in vivo and in vitro phenotype readouts; replicated across multiple GRA knockouts in same study","pmids":["31266861"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":"Prugniaud (Pru) type II"}]},{"year":2019,"finding":"TgGRA3 interacts with host Golgi membranes, oligomerizes, and promotes the formation of tubules and entry of host Golgi material into the PV; disruption of the TgGRA3 gene delays engulfment of host Golgi; GRA3 dysregulates anterograde transport in the host cell.","method":"Gene disruption (ΔgGRA3), live imaging/fluorescence microscopy of host Golgi, biochemical binding assay of GRA3 to isolated Golgi membranes, oligomerization analysis","journal":"Biology open","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO with specific host organelle phenotype plus direct binding to Golgi membranes; single lab, two orthogonal approaches","pmids":["30814066"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2022,"finding":"GRA3 (Wh6 allele) induces neuronal apoptosis via ER stress by activating the PERK pathway; transfection of N2a cells with GRA3Wh6 increased GRP78, p-PERK, cleaved caspase-12, cleaved caspase-3, and CHOP; PERK inhibitor GSK2656157 and caspase-12 inhibitor Z-ATAD-FMK reduced GRA3-induced apoptosis.","method":"Plasmid transfection of N2a cells with pEGFP-GRA3Wh6, flow cytometry (apoptosis), immunoblotting for ER stress/apoptosis markers, pharmacological inhibitors (GSK2656157, Z-ATAD-FMK)","journal":"Parasites & vectors","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — overexpression with pharmacological pathway intervention; multiple downstream markers; single lab","pmids":["35918751"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":"Chinese 1 Wh6"}]},{"year":2023,"finding":"GRA3-deficient T. gondii cysts showed significantly enhanced elimination by anti-cyst CD8+ T cells (perforin-mediated) compared to wild-type; cysts that persisted in the presence of CD8+ T cells had significantly greater GRA3 mRNA levels than the total cyst population; GRA3 mRNA levels correlated with successful cyst persistence during active T-cell immunity.","method":"GRA3-deficient parasite strain, in vivo cyst burden measurement in BALB/c mice with CD8+ T-cell immunity, qRT-PCR of GRA3 mRNA in persisting vs. total cysts, correlation analysis","journal":"Frontiers in immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO with defined immunological phenotype plus correlative mRNA analysis; single lab","pmids":["37868957"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2019,"finding":"Deletion of GRA3 (PVM-associated) did not affect the antitumor immunity activated by uracil auxotrophic T. gondii mutants, in contrast to deletions of GRA2, GRA12, GRA24, ROP5, ROP17, ROP18, and ROP35, which severely abrogated the antitumor response.","method":"Targeted gene deletion in Δku80 vaccine strain, tumor model (established ovarian cancer), flow cytometry, cytokine measurement","journal":"PLoS genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO with specific in vivo phenotypic readout; negative result for GRA3 is mechanistically informative","pmids":["27447180"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":"type I Δku80"}]},{"year":2026,"finding":"GRA3 interacts with host STING, promotes STING oligomerization, and nuclear translocation of phosphorylated IRF3, enhancing IFN-β production via the cGAS-STING pathway; GRA3 also promotes STAT6 phosphorylation; the net effect is enhanced parasite proliferation mediated by ISG56 and STAT6 rather than IFN-β itself.","method":"Co-immunoprecipitation (GRA3-STING interaction), STING oligomerization assay, nuclear fractionation (p-IRF3 translocation), gene KO/overexpression, IFN-β ELISA, ISG56/STAT6 inhibitor/KO experiments, parasite proliferation assays","journal":"PLoS neglected tropical diseases","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus functional downstream assays with KO; single lab, multiple orthogonal methods","pmids":["41712610"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":"ME49"}]},{"year":2025,"finding":"CRISPR/Cas9-generated ME49Δgra3 parasites show reduced plaque number, a lower proportion of PVs with ≥4 tachyzoites, and significantly increased host mortality in C57BL/6 mice (70% vs 10% at 35 days), demonstrating that GRA3 promotes intracellular replication and virulence in the ME49 type II strain.","method":"CRISPR/Cas9 gene disruption, Western blot confirmation of protein absence, crystal violet plaque assay, Giemsa staining of PV sizes, mouse survival experiment","journal":"Zhongguo xue xi chong bing fang zhi za zhi","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CRISPR KO with Western blot validation and multiple in vitro and in vivo phenotypic readouts; single lab","pmids":["40730529"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":"ME49"}]},{"year":2019,"finding":"GRA3 (along with GRA2, GRA4, GRA5, GRA7, GRA12) was found in a proteomic characterization of purified cyst wall fragments from in vitro T. gondii cysts, establishing GRA3 as a component of the cyst wall.","method":"Percoll gradient enrichment of cyst wall fragments, CST1 immunoprecipitation, LC-MS/MS proteomic analysis","journal":"mBio","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — proteomic identification in purified preparation; no direct functional follow-up on GRA3 specifically","pmids":["31040239"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2019,"finding":"Deletion of GRA3 increased MHC-I antigen presentation of PV-localized parasite antigens to CD8+ T cells in infected macrophages and/or dendritic cells, indicating that GRA3 suppresses antigen presentation; this suppression operated independently of IFN-γ or IRG effectors (unlike GRA7/ROP5/ROP18).","method":"Targeted GRA3 deletion, MHC-I antigen presentation assay with CD8+ T cells, macrophage and dendritic cell infection, ±IFN-γ conditions, comparison with IRG-dependent effectors","journal":"Frontiers in immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO with specific T-cell recognition readout; single lab, mechanistic comparison to other effectors","pmids":["31555296"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":"type II"}]}],"current_model":"GRA3 is a type I transmembrane dense granule protein with an N-terminal signal sequence and a C-terminal dilysine ER retrieval motif that is stored as a soluble oligomer in dense granules, secreted constitutively via the NSF/SNAP/SNARE/Rab machinery upon host-cell invasion, and then inserts into the parasitophorous vacuole membrane (PVM) in an oligomeric form through hydrophobic interactions; from the PVM it interacts with the host ER protein CAMLG (recruiting ER to the PVM), binds host Golgi membranes to promote Golgi tubulation and entry of Golgi material into the PV while dysregulating anterograde transport, interacts with host STING to activate the cGAS-STING/IRF3/ISG56 and STAT6 axes to enhance parasite proliferation, induces ER stress-mediated neuronal apoptosis via the PERK pathway, suppresses MHC-I antigen presentation to CD8+ T cells, and contributes to acute virulence, chronic cyst persistence, and evasion of CD8+ T-cell immunity in vivo."},"narrative":{"mechanistic_narrative":"GRA3 is a Toxoplasma gondii dense granule protein that is secreted into the parasitophorous vacuole upon host-cell invasion and functions from the parasitophorous vacuole membrane (PVM) as an interface for co-opting host organelles and modulating host immunity [PMID:8195173, PMID:7739670, PMID:19127325]. It is a 24 kDa protein carrying an N-terminal secretory signal sequence, a transmembrane domain, and a C-terminal dilysine (KKXX) ER-retrieval motif; the signal peptide alone is necessary and sufficient to target reporter protein to dense granules and the PV [PMID:16149193]. Stored as a soluble protein in dense granules, GRA3 is released by constitutive, calcium-independent exocytosis mediated by the NSF/SNAP/SNARE/Rab machinery and inserts directly into the PVM in an oligomeric form through hydrophobic interactions, self-cross-linking without incorporating other parasite or host proteins [PMID:8195173, PMID:9891012]. From the PVM, GRA3 engages host membranes and signaling: it binds the host ER protein CAMLG, recruiting ER to the PVM [PMID:19127325]; it binds host Golgi membranes, oligomerizes, and drives Golgi tubulation and entry of Golgi material into the PV [PMID:30814066]; and it interacts with host STING to promote STING oligomerization and IRF3 nuclear translocation, engaging the cGAS-STING and STAT6 axes to enhance parasite proliferation via ISG56 and STAT6 [PMID:41712610]. GRA3 suppresses MHC-I antigen presentation of PV-localized antigens to CD8+ T cells independently of IFN-γ/IRG effectors [PMID:31555296], and contributes to intracellular replication, acute virulence, and chronic cyst persistence in vivo [PMID:17418907, PMID:31266861, PMID:40730529, PMID:37868957], where it is also a component of the cyst wall [PMID:31040239]. Expressed in tachyzoites but absent from sporozoites [PMID:8720177], GRA3 (Wh6 allele) can additionally trigger PERK-dependent ER-stress apoptosis in neuronal cells when overexpressed [PMID:35918751].","teleology":[{"year":1993,"claim":"Established when and where GRA3 is delivered to the host interface, showing dense granule discharge occurs at the apical pole within minutes of invasion and deposits GRA3 at the nascent PVM.","evidence":"IFA, immunoelectron microscopy, and freeze-fracture at defined post-invasion time points in T. gondii","pmids":["8415546"],"confidence":"High","gaps":["Did not define the biochemical mechanism of membrane insertion","Did not identify host partners at the PVM"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":1994,"claim":"Answered how a soluble dense granule protein becomes membrane-associated, showing GRA3 inserts directly into the vacuole membrane as a self-associating oligomer via hydrophobic interactions rather than through a stable partner complex.","evidence":"Sucrose flotation, Triton X-114 partitioning, carbonate extraction, and chemical cross-linking in T. gondii","pmids":["8195173"],"confidence":"High","gaps":["Sequence used was later shown to be a chimera","Topology and orientation of the inserted protein not resolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":1994,"claim":"Defined the molecular architecture by cloning GRA3 cDNA and demonstrating an N-terminal signal sequence sufficient for dense granule/PV targeting, though the original sequence carried an error.","evidence":"cDNA cloning, in vitro translation with dog pancreas microsomes, IFA, Southern/Northern blot in T. gondii","pmids":["7739670"],"confidence":"High","gaps":["Reported sequence and MW later corrected","Function beyond localization not addressed"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":1995,"claim":"Established stage-specific expression, showing GRA3 is absent from sporozoites and appears at tachyzoite conversion, tying its function to the replicative intracellular stage.","evidence":"IFA and Western blot time course in sporozoite-infected cells in T. gondii","pmids":["8720177"],"confidence":"Medium","gaps":["Regulatory basis of stage-specific expression not addressed","Sporozoite-stage functional consequence not tested"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":1999,"claim":"Defined the secretion pathway, showing GRA3 release is constitutive, calcium-independent, and dependent on NSF/SNAP/SNARE/Rab machinery.","evidence":"Endogenous secretion assay in SLO-permeabilized parasites with recombinant NSF/α-SNAP and inhibitors (NEM, Rab-GDI) in T. gondii","pmids":["9891012"],"confidence":"High","gaps":["Specific SNARE/Rab identities not defined","Trigger coupling secretion to invasion not resolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2005,"claim":"Corrected the primary structure, establishing authentic GRA3 as a 24 kDa protein with signal sequence, transmembrane domain, and a C-terminal dilysine ER-retrieval motif consistent with PVM insertion.","evidence":"Sequence analysis, recombinant antibody, GFP targeting, and ESA immunoblot in T. gondii","pmids":["16149193"],"confidence":"High","gaps":["Functional role of the KKXX motif not experimentally tested","Host-facing versus lumenal domain topology unresolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2007,"claim":"Delineated GRA3's oligomeric behavior relative to other GRA proteins, showing it co-purifies with soluble GRA2/GRA6/GRA7 complexes but dissociates from GRA2 after membrane insertion.","evidence":"HA-FLAG affinity purification from complemented KO parasites with MS in T. gondii","pmids":["17959262"],"confidence":"High","gaps":["Whether GRA3 forms independent oligomers versus mixed complexes in the membrane unresolved","Stoichiometry not defined"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2007,"claim":"Provided the first genetic test of function, showing GRA3 is dispensable for in vitro growth and bradyzoite formation but contributes to acute virulence in vivo, restorable by complementation.","evidence":"Homologous-recombination KO with complementation and mouse survival in a type II strain of T. gondii","pmids":["17418907"],"confidence":"High","gaps":["Molecular mechanism of virulence contribution not identified","Host pathways affected not defined"],"attribution":[{"species":"Toxoplasma gondii","strain":"type II"}]},{"year":2008,"claim":"Identified the first host-cell partner, showing PVM-inserted GRA3 binds the host ER protein CAMLG, providing a molecular basis for ER recruitment to the PVM.","evidence":"Yeast two-hybrid, GST pull-down, co-IP, and co-localization in infected cells for T. gondii","pmids":["19127325"],"confidence":"Medium","gaps":["Functional consequence of ER recruitment for the parasite not tested","Interaction not validated in a knockout background"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2008,"claim":"Placed GRA3 within cytosolic strand-like extensions of the PVM alongside GRA1, GRA7, and rhoptry proteins, extending its localization beyond the vacuole membrane proper.","evidence":"Multi-protein co-labeling IFA at defined time points in T. gondii","pmids":["18809661"],"confidence":"Medium","gaps":["Functional role of GRA3 in strand structures not defined","Fixed-cell co-localization only"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2016,"claim":"Distinguished GRA3 from IRG-modulating effectors by showing it is dispensable for the antitumor immunity induced by uracil-auxotroph vaccines, unlike GRA2/GRA12/GRA24 and several ROPs.","evidence":"Targeted deletion in Δku80 vaccine strain with ovarian tumor model and immune readouts in type I T. gondii","pmids":["27447180"],"confidence":"Medium","gaps":["Does not exclude a role in other immune contexts","Negative result in a specific vaccine setting only"],"attribution":[{"species":"Toxoplasma gondii","strain":"type I Δku80"}]},{"year":2019,"claim":"Revealed GRA3's role in host Golgi hijacking, showing it binds Golgi membranes, oligomerizes, and promotes Golgi tubulation and engulfment into the PV while dysregulating anterograde transport.","evidence":"Gene disruption with live host-Golgi imaging and direct Golgi membrane binding assays in T. gondii","pmids":["30814066"],"confidence":"Medium","gaps":["Direct GRA3 receptor on Golgi not identified","Parasite benefit of Golgi engulfment not quantified"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2019,"claim":"Established a chronic-stage requirement, showing GRA3 deletion in the Pru type II strain severely impairs in vivo cyst development while sparing growth and in vitro differentiation.","evidence":"Targeted deletion with in vivo cyst burden and in vitro bradyzoite assays in Pru type II T. gondii","pmids":["31266861"],"confidence":"High","gaps":["Molecular basis of the cyst defect not defined","Whether the defect is intrinsic or immune-driven unresolved"],"attribution":[{"species":"Toxoplasma gondii","strain":"Prugniaud (Pru) type II"}]},{"year":2019,"claim":"Identified GRA3 as a cyst-wall component, linking its PVM/interface role to the chronic-stage structure.","evidence":"Percoll-enriched cyst wall fragments with CST1 IP and LC-MS/MS in T. gondii","pmids":["31040239"],"confidence":"Medium","gaps":["Functional contribution to cyst wall integrity not tested","Association versus structural role not distinguished"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2019,"claim":"Defined an immune-evasion function, showing GRA3 suppresses MHC-I presentation of PV antigens to CD8+ T cells independently of IFN-γ/IRG effectors.","evidence":"GRA3 deletion with MHC-I antigen presentation assays in macrophages and dendritic cells ±IFN-γ in type II T. gondii","pmids":["31555296"],"confidence":"Medium","gaps":["Molecular mechanism of antigen presentation suppression not identified","Relevant host trafficking step not defined"],"attribution":[{"species":"Toxoplasma gondii","strain":"type II"}]},{"year":2022,"claim":"Uncovered a host-cell-death consequence, showing overexpressed GRA3 (Wh6 allele) triggers PERK-dependent ER-stress apoptosis in neuronal cells.","evidence":"Overexpression in N2a cells with ER-stress/apoptosis marker immunoblotting and PERK/caspase-12 inhibitors in Chinese 1 Wh6 T. gondii","pmids":["35918751"],"confidence":"Medium","gaps":["Demonstrated by overexpression rather than in infection","Allele-specificity versus general GRA3 effect not resolved"],"attribution":[{"species":"Toxoplasma gondii","strain":"Chinese 1 Wh6"}]},{"year":2023,"claim":"Linked GRA3 to CD8+ T-cell resistance during chronic infection, showing GRA3-deficient cysts are more efficiently eliminated by perforin-dependent CD8+ T cells and that persisting cysts are enriched for GRA3 mRNA.","evidence":"GRA3-deficient strain with in vivo cyst burden under CD8+ immunity and qRT-PCR correlation in BALB/c mice with T. gondii","pmids":["37868957"],"confidence":"Medium","gaps":["Causal versus correlative role of GRA3 mRNA in persistence not resolved","Link to MHC-I suppression mechanism not directly tested"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2025,"claim":"Confirmed GRA3's contribution to replication and virulence with CRISPR deletion, showing ME49Δgra3 has reduced plaque formation, smaller PVs, and increased host mortality.","evidence":"CRISPR/Cas9 disruption with Western validation, plaque and PV-size assays, and mouse survival in ME49 T. gondii","pmids":["40730529"],"confidence":"Medium","gaps":["Increased mortality mechanism not dissected","Molecular pathway linking GRA3 to replication not defined here"],"attribution":[{"species":"Toxoplasma gondii","strain":"ME49"}]},{"year":2026,"claim":"Identified a signaling mechanism for GRA3-driven proliferation, showing GRA3 binds host STING to promote STING oligomerization, IRF3 nuclear translocation, and STAT6 phosphorylation, with proliferation mediated by ISG56 and STAT6 rather than IFN-β.","evidence":"Co-IP, STING oligomerization and nuclear fractionation assays, KO/overexpression, and ISG56/STAT6 KO/inhibitor proliferation assays in ME49 T. gondii","pmids":["41712610"],"confidence":"Medium","gaps":["Direct binding interface with STING not mapped","How PVM-restricted GRA3 accesses host STING not resolved"],"attribution":[{"species":"Toxoplasma gondii","strain":"ME49"}]},{"year":null,"claim":"How GRA3's single membrane insertion domain simultaneously coordinates ER (CAMLG), Golgi, and STING engagement, and whether these interactions are physically or temporally partitioned, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of GRA3 at the PVM","Topology dictating which domains face the host cytosol undefined","Mechanistic link between host-organelle capture, immune evasion, and cyst persistence not integrated"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["Homo-oligomeric GRA3 assembly in the PVM (self-cross-linking)","Soluble GRA2/GRA3/GRA6/GRA7 co-purifying complex prior to membrane insertion"],"partners":["CAMLG (HOST ER TYPE II TRANSMEMBRANE PROTEIN)","HOST GOLGI MEMBRANES","HOST STING","GRA2, GRA6, GRA7 (SOLUBLE COMPLEX, PRE-INSERTION)","NSF / Α-SNAP / SNARE / RAB (SECRETION MACHINERY)"],"other_free_text":["24 kDa type I transmembrane dense granule protein with N-terminal signal sequence and C-terminal dilysine (KKXX) ER-retrieval motif [#4]","Originally published sequence was a chimera; authentic protein defined in 2005 [#4]","Expressed in tachyzoites but absent from sporozoites, appearing at tachyzoite conversion [#9]","Component of the in vitro cyst wall proteome [#17]","Dispensable for in vitro growth/differentiation but required for chronic cyst persistence and contributes to acute virulence [#6, #10, #16]","GRA3 mRNA levels correlate with cyst persistence under CD8+ T-cell immunity [#13]","Not required for uracil-auxotroph vaccine antitumor immunity, unlike several other GRA/ROP effectors [#14]"]},"strain_conflicts":[]},"prefetch_data":{},"corpus_meta":[{"pmid":"8415546","id":"PMC_8415546","title":"Kinetics and pattern of organelle exocytosis during Toxoplasma gondii/host-cell interaction.","date":"1993","source":"Parasitology research","url":"https://pubmed.ncbi.nlm.nih.gov/8415546","citation_count":158,"is_preprint":false},{"pmid":"12717631","id":"PMC_12717631","title":"Serotyping of Toxoplasma gondii infections in humans using synthetic peptides.","date":"2003","source":"The Journal of infectious diseases","url":"https://pubmed.ncbi.nlm.nih.gov/12717631","citation_count":106,"is_preprint":false},{"pmid":"18809661","id":"PMC_18809661","title":"The Toxoplasma gondii dense granule protein GRA7 is phosphorylated upon invasion and forms an unexpected association with the rhoptry proteins ROP2 and ROP4.","date":"2008","source":"Infection and immunity","url":"https://pubmed.ncbi.nlm.nih.gov/18809661","citation_count":78,"is_preprint":false},{"pmid":"31266861","id":"PMC_31266861","title":"Toxoplasma gondii Parasitophorous Vacuole Membrane-Associated Dense Granule Proteins Orchestrate Chronic Infection and GRA12 Underpins Resistance to Host Gamma Interferon.","date":"2019","source":"mBio","url":"https://pubmed.ncbi.nlm.nih.gov/31266861","citation_count":75,"is_preprint":false},{"pmid":"16757610","id":"PMC_16757610","title":"Chimeric antigens of Toxoplasma gondii: toward standardization of toxoplasmosis serodiagnosis using recombinant 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protein microarray approach screening sera of murine model infected orally with oocysts and tissue cysts.","date":"2018","source":"Parasites & vectors","url":"https://pubmed.ncbi.nlm.nih.gov/29973272","citation_count":24,"is_preprint":false},{"pmid":"15850804","id":"PMC_15850804","title":"Host cell binding of GRA10, a novel, constitutively secreted dense granular protein from Toxoplasma gondii.","date":"2005","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/15850804","citation_count":22,"is_preprint":false},{"pmid":"31555296","id":"PMC_31555296","title":"Rhoptry and Dense Granule Secreted Effectors Regulate CD8+ T Cell Recognition of Toxoplasma gondii Infected Host Cells.","date":"2019","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/31555296","citation_count":21,"is_preprint":false},{"pmid":"22072819","id":"PMC_22072819","title":"Development and clinical evaluation of a rapid serodiagnostic test for toxoplasmosis of cats using recombinant SAG1 antigen.","date":"2011","source":"The Korean journal of parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/22072819","citation_count":19,"is_preprint":false},{"pmid":"30814066","id":"PMC_30814066","title":"The Toxoplasma gondii dense granule protein TgGRA3 interacts with host Golgi and dysregulates anterograde transport.","date":"2019","source":"Biology open","url":"https://pubmed.ncbi.nlm.nih.gov/30814066","citation_count":19,"is_preprint":false},{"pmid":"29157292","id":"PMC_29157292","title":"Genotyping of polymorphic effectors of Toxoplasma gondii isolates from China.","date":"2017","source":"Parasites & vectors","url":"https://pubmed.ncbi.nlm.nih.gov/29157292","citation_count":13,"is_preprint":false},{"pmid":"35918751","id":"PMC_35918751","title":"Toxoplasma gondii dense granule protein 3 promotes endoplasmic reticulum stress-induced apoptosis by activating the PERK pathway.","date":"2022","source":"Parasites & 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pigs.","date":"2024","source":"Frontiers in cellular and infection microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/38720960","citation_count":3,"is_preprint":false},{"pmid":"34039408","id":"PMC_34039408","title":"Proteomics analysis reveals that the proto-oncogene eIF-5A indirectly influences the growth, invasion and replication of Toxoplasma gondii tachyzoite.","date":"2021","source":"Parasites & vectors","url":"https://pubmed.ncbi.nlm.nih.gov/34039408","citation_count":3,"is_preprint":false},{"pmid":"36977144","id":"PMC_36977144","title":"Preparation and Preliminary Application of Epitope Peptide-Based Antibody against Toxoplasma gondii GRA3.","date":"2023","source":"Tropical medicine and infectious disease","url":"https://pubmed.ncbi.nlm.nih.gov/36977144","citation_count":2,"is_preprint":false},{"pmid":"38898997","id":"PMC_38898997","title":"Comparison of the performance of SAG2, GRA6, and GRA7 for serological diagnosis of Toxoplasma gondii infection in 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testing].","date":"2025","source":"Zhongguo xue xi chong bing fang zhi za zhi = Chinese journal of schistosomiasis control","url":"https://pubmed.ncbi.nlm.nih.gov/40730529","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":24603,"output_tokens":5587,"usd":0.078807,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":12529,"output_tokens":6980,"usd":0.118572,"stage2_stop_reason":"end_turn"},"total_usd":0.197379,"stage1_batch_id":"msgbatch_01XFXJD6iZecXyWn9uU5Qom9","stage2_batch_id":"msgbatch_013GToKgs4AKSCRE4yvueviH","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1994,\n      \"finding\": \"GRA3 is stored as a soluble protein in dense granules and, following secretion into the parasitophorous vacuole, inserts directly into the vacuole membrane in an oligomeric form via hydrophobic interactions; it cannot be removed by sodium carbonate extraction, is not labeled by [1-14C]acetate, and cross-links to itself (forming a ladder on SDS-PAGE) but no other parasite or host proteins co-precipitate with cross-linked GRA3.\",\n      \"method\": \"Sucrose flotation gradients, Triton X-114 phase partitioning, sodium carbonate extraction, chemical cross-linking, SDS-PAGE, [1-14C]acetate labeling\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — multiple orthogonal biochemical methods in a single rigorous study establishing mechanism of membrane insertion\",\n      \"pmids\": [\"8195173\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"GRA3 cDNA encodes a 30 kDa protein with an N-terminal signal sequence (sufficient to target GFP to dense granules and PV) and four short hydrophobic regions insufficient to span the membrane; Southern blot indicates a single-copy gene; GRA3 localizes to dense granules, the PVM, and PVM extensions protruding into the host cytoplasm.\",\n      \"method\": \"cDNA cloning, Northern blot, Southern blot, in vitro translation with dog pancreas microsomes, immunofluorescence, immunoblot with affinity-purified antibodies\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — multiple orthogonal molecular methods; signal peptide function confirmed by in vitro translation with microsomes\",\n      \"pmids\": [\"7739670\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1993,\n      \"finding\": \"Dense granule exocytosis (releasing GRA2 and GRA3) occurs in the apical area of the tachyzoite within minutes of invasion; dense granule contents appear first as dense material between parasite and vacuole membranes before the vacuolar network or PVM are immunolabeled; GRA3 antibodies label the PVM and strands extending from PVs into the host-cell cytoplasm.\",\n      \"method\": \"Immunofluorescence assay (IFA), immunoelectron microscopy, serial sectioning, freeze-fracture studies at defined post-invasion time points\",\n      \"journal\": \"Parasitology research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple imaging modalities with temporal resolution; replicated in same study by independent methods\",\n      \"pmids\": [\"8415546\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"GRA3 release from dense granules is constitutive and calcium-independent; the NSF/SNAP/SNARE/Rab machinery mediates dense granule exocytosis, as shown by inhibition with N-ethylmaleimide and Rab-GDI, and augmentation with recombinant NSF and α-SNAP in streptolysin O-permeabilized parasites.\",\n      \"method\": \"Endogenous GRA3 secretion assay in intact and SLO-permeabilized parasites, recombinant protein addition, pharmacological inhibitors (NEM, Rab-GDI), GTPγS and cAMP treatments\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstitution with recombinant components plus pharmacological inhibitors in permeabilized parasite system, multiple orthogonal interventions\",\n      \"pmids\": [\"9891012\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The originally published GRA3 sequence is an artificial chimera of two proteins. The authentic GRA3 (24 kDa, recognized by mAb 2H11) contains an N-terminal secretory signal sequence and a transmembrane domain consistent with PVM insertion, plus a C-terminal dilysine (KKXX) ER retrieval motif. The signal peptide alone is necessary and sufficient to target GFP to dense granules and the PV. A Neospora caninum homologue was identified.\",\n      \"method\": \"Sequence analysis, recombinant antibody production, immunoblot of ESA, GFP fusion/targeting assay, bioinformatics identification of KKXX motif\",\n      \"journal\": \"Parasitology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — sequence correction validated by antibody recognition of correct MW protein plus GFP targeting experiment; single lab but multiple orthogonal methods\",\n      \"pmids\": [\"16149193\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Within the parasite and the PV soluble fraction, GRA2 and GRA5 form high-molecular-weight oligomeric complexes with multiple GRA proteins; affinity purification of HA-FLAG-tagged GRA2 from ΔeGRA2 complemented parasites co-purified GRA3, GRA6, and GRA7 as the major partners. After membrane insertion, GRA2 associates with GRA5 and GRA7 but not GRA3.\",\n      \"method\": \"Affinity chromatography (HA-FLAG tag), conventional chromatography, complementation of KO parasites with tagged proteins, co-purification/MS\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal affinity purification from complemented KO parasites with MS identification; single lab, multiple orthogonal approaches\",\n      \"pmids\": [\"17959262\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Targeted deletion of GRA3 in a type II strain shows no effect on cell culture growth rate or bradyzoite formation, and does not alter localization of other dense granule proteins or association with host cell organelles; however, at ~4× the LD50, ΔeGRA3 mice survived acute infection, and complementation restored and even enhanced virulence, demonstrating GRA3 contributes to acute virulence in vivo.\",\n      \"method\": \"Homologous recombination gene knockout, plaque assay, bradyzoite differentiation assay, IFA for GRA protein localization, mouse survival experiments, genetic complementation\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with complementation rescue in mouse virulence model; multiple cellular phenotypes tested; single lab\",\n      \"pmids\": [\"17418907\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"type II\"}]\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"PVM-inserted GRA3 physically interacts with CAMLG (calcium modulating ligand), a type II transmembrane protein of the host cell ER, as established by yeast two-hybrid screening of a HeLa cDNA library, GST pull-down, and co-immunoprecipitation; GRA3 and CAMLG co-localize at the PVM in infected cells, suggesting GRA3 mediates ER recruitment to the PVM.\",\n      \"method\": \"Yeast two-hybrid (GRA3 ORF vs HeLa cDNA library), GST pull-down assay, co-immunoprecipitation, co-transfection/co-localization by fluorescence microscopy, IFA in infected cells\",\n      \"journal\": \"The Korean journal of parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — three orthogonal binding assays (Y2H, GST pull-down, Co-IP) plus co-localization; single lab\",\n      \"pmids\": [\"19127325\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"GRA7 strands in the host cytosol (formed within 10 min of invasion) also contain GRA1 and GRA3, indicating GRA3 is present in cytosolic strand-like structures alongside rhoptry proteins ROP2 and ROP4 in infected host cells.\",\n      \"method\": \"IFA with co-labeling of GRA7, GRA1, GRA3, ROP2, ROP4 at defined post-invasion time points\",\n      \"journal\": \"Infection and immunity\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — single co-localization study; co-labeling in fixed cells; independently observed for multiple proteins\",\n      \"pmids\": [\"18809661\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"Sporozoites of T. gondii lack GRA3 protein (not detected by IFA or Western blot in sporozoite-infected cells 2–15 h post-inoculation); GRA3 expression first appears 15 h post-inoculation and is present in all intracellular parasites at 24 h, coinciding with expression of the tachyzoite marker SAG1 and onset of replication.\",\n      \"method\": \"Indirect immunofluorescence, Western blot of sporozoite extracts, time-course monitoring of GRA3 and SAG1 expression\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — IFA and Western blot with temporal resolution; negative result rigorously established in sporozoites\",\n      \"pmids\": [\"8720177\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Deletion of PVM-associated GRA3 in the type II Prugniaud strain induced severe defects in chronic cyst development in vivo without affecting parasite growth rate or in vitro cyst differentiation; acute virulence of PruΔgra3 was reduced but not abolished.\",\n      \"method\": \"Targeted gene deletion (Δgra3) in type II Pru strain, in vivo mouse cyst burden assay, in vitro bradyzoite differentiation, plaque assay\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO in low-virulence strain with both in vivo and in vitro phenotype readouts; replicated across multiple GRA knockouts in same study\",\n      \"pmids\": [\"31266861\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"Prugniaud (Pru) type II\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"TgGRA3 interacts with host Golgi membranes, oligomerizes, and promotes the formation of tubules and entry of host Golgi material into the PV; disruption of the TgGRA3 gene delays engulfment of host Golgi; GRA3 dysregulates anterograde transport in the host cell.\",\n      \"method\": \"Gene disruption (ΔgGRA3), live imaging/fluorescence microscopy of host Golgi, biochemical binding assay of GRA3 to isolated Golgi membranes, oligomerization analysis\",\n      \"journal\": \"Biology open\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO with specific host organelle phenotype plus direct binding to Golgi membranes; single lab, two orthogonal approaches\",\n      \"pmids\": [\"30814066\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"GRA3 (Wh6 allele) induces neuronal apoptosis via ER stress by activating the PERK pathway; transfection of N2a cells with GRA3Wh6 increased GRP78, p-PERK, cleaved caspase-12, cleaved caspase-3, and CHOP; PERK inhibitor GSK2656157 and caspase-12 inhibitor Z-ATAD-FMK reduced GRA3-induced apoptosis.\",\n      \"method\": \"Plasmid transfection of N2a cells with pEGFP-GRA3Wh6, flow cytometry (apoptosis), immunoblotting for ER stress/apoptosis markers, pharmacological inhibitors (GSK2656157, Z-ATAD-FMK)\",\n      \"journal\": \"Parasites & vectors\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — overexpression with pharmacological pathway intervention; multiple downstream markers; single lab\",\n      \"pmids\": [\"35918751\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"Chinese 1 Wh6\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"GRA3-deficient T. gondii cysts showed significantly enhanced elimination by anti-cyst CD8+ T cells (perforin-mediated) compared to wild-type; cysts that persisted in the presence of CD8+ T cells had significantly greater GRA3 mRNA levels than the total cyst population; GRA3 mRNA levels correlated with successful cyst persistence during active T-cell immunity.\",\n      \"method\": \"GRA3-deficient parasite strain, in vivo cyst burden measurement in BALB/c mice with CD8+ T-cell immunity, qRT-PCR of GRA3 mRNA in persisting vs. total cysts, correlation analysis\",\n      \"journal\": \"Frontiers in immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO with defined immunological phenotype plus correlative mRNA analysis; single lab\",\n      \"pmids\": [\"37868957\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Deletion of GRA3 (PVM-associated) did not affect the antitumor immunity activated by uracil auxotrophic T. gondii mutants, in contrast to deletions of GRA2, GRA12, GRA24, ROP5, ROP17, ROP18, and ROP35, which severely abrogated the antitumor response.\",\n      \"method\": \"Targeted gene deletion in Δku80 vaccine strain, tumor model (established ovarian cancer), flow cytometry, cytokine measurement\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with specific in vivo phenotypic readout; negative result for GRA3 is mechanistically informative\",\n      \"pmids\": [\"27447180\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"type I Δku80\"}]\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"GRA3 interacts with host STING, promotes STING oligomerization, and nuclear translocation of phosphorylated IRF3, enhancing IFN-β production via the cGAS-STING pathway; GRA3 also promotes STAT6 phosphorylation; the net effect is enhanced parasite proliferation mediated by ISG56 and STAT6 rather than IFN-β itself.\",\n      \"method\": \"Co-immunoprecipitation (GRA3-STING interaction), STING oligomerization assay, nuclear fractionation (p-IRF3 translocation), gene KO/overexpression, IFN-β ELISA, ISG56/STAT6 inhibitor/KO experiments, parasite proliferation assays\",\n      \"journal\": \"PLoS neglected tropical diseases\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus functional downstream assays with KO; single lab, multiple orthogonal methods\",\n      \"pmids\": [\"41712610\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"ME49\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CRISPR/Cas9-generated ME49Δgra3 parasites show reduced plaque number, a lower proportion of PVs with ≥4 tachyzoites, and significantly increased host mortality in C57BL/6 mice (70% vs 10% at 35 days), demonstrating that GRA3 promotes intracellular replication and virulence in the ME49 type II strain.\",\n      \"method\": \"CRISPR/Cas9 gene disruption, Western blot confirmation of protein absence, crystal violet plaque assay, Giemsa staining of PV sizes, mouse survival experiment\",\n      \"journal\": \"Zhongguo xue xi chong bing fang zhi za zhi\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR KO with Western blot validation and multiple in vitro and in vivo phenotypic readouts; single lab\",\n      \"pmids\": [\"40730529\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"ME49\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"GRA3 (along with GRA2, GRA4, GRA5, GRA7, GRA12) was found in a proteomic characterization of purified cyst wall fragments from in vitro T. gondii cysts, establishing GRA3 as a component of the cyst wall.\",\n      \"method\": \"Percoll gradient enrichment of cyst wall fragments, CST1 immunoprecipitation, LC-MS/MS proteomic analysis\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — proteomic identification in purified preparation; no direct functional follow-up on GRA3 specifically\",\n      \"pmids\": [\"31040239\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Deletion of GRA3 increased MHC-I antigen presentation of PV-localized parasite antigens to CD8+ T cells in infected macrophages and/or dendritic cells, indicating that GRA3 suppresses antigen presentation; this suppression operated independently of IFN-γ or IRG effectors (unlike GRA7/ROP5/ROP18).\",\n      \"method\": \"Targeted GRA3 deletion, MHC-I antigen presentation assay with CD8+ T cells, macrophage and dendritic cell infection, ±IFN-γ conditions, comparison with IRG-dependent effectors\",\n      \"journal\": \"Frontiers in immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with specific T-cell recognition readout; single lab, mechanistic comparison to other effectors\",\n      \"pmids\": [\"31555296\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"type II\"}]\n    }\n  ],\n  \"current_model\": \"GRA3 is a type I transmembrane dense granule protein with an N-terminal signal sequence and a C-terminal dilysine ER retrieval motif that is stored as a soluble oligomer in dense granules, secreted constitutively via the NSF/SNAP/SNARE/Rab machinery upon host-cell invasion, and then inserts into the parasitophorous vacuole membrane (PVM) in an oligomeric form through hydrophobic interactions; from the PVM it interacts with the host ER protein CAMLG (recruiting ER to the PVM), binds host Golgi membranes to promote Golgi tubulation and entry of Golgi material into the PV while dysregulating anterograde transport, interacts with host STING to activate the cGAS-STING/IRF3/ISG56 and STAT6 axes to enhance parasite proliferation, induces ER stress-mediated neuronal apoptosis via the PERK pathway, suppresses MHC-I antigen presentation to CD8+ T cells, and contributes to acute virulence, chronic cyst persistence, and evasion of CD8+ T-cell immunity in vivo.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"GRA3 is a Toxoplasma gondii dense granule protein that is secreted into the parasitophorous vacuole upon host-cell invasion and functions from the parasitophorous vacuole membrane (PVM) as an interface for co-opting host organelles and modulating host immunity [#0, #1, #7]. It is a 24 kDa protein carrying an N-terminal secretory signal sequence, a transmembrane domain, and a C-terminal dilysine (KKXX) ER-retrieval motif; the signal peptide alone is necessary and sufficient to target reporter protein to dense granules and the PV [#4]. Stored as a soluble protein in dense granules, GRA3 is released by constitutive, calcium-independent exocytosis mediated by the NSF/SNAP/SNARE/Rab machinery and inserts directly into the PVM in an oligomeric form through hydrophobic interactions, self-cross-linking without incorporating other parasite or host proteins [#0, #3]. From the PVM, GRA3 engages host membranes and signaling: it binds the host ER protein CAMLG, recruiting ER to the PVM [#7]; it binds host Golgi membranes, oligomerizes, and drives Golgi tubulation and entry of Golgi material into the PV [#11]; and it interacts with host STING to promote STING oligomerization and IRF3 nuclear translocation, engaging the cGAS-STING and STAT6 axes to enhance parasite proliferation via ISG56 and STAT6 [#15]. GRA3 suppresses MHC-I antigen presentation of PV-localized antigens to CD8+ T cells independently of IFN-\\u03b3/IRG effectors [#18], and contributes to intracellular replication, acute virulence, and chronic cyst persistence in vivo [#6, #10, #16, #13], where it is also a component of the cyst wall [#17]. Expressed in tachyzoites but absent from sporozoites [#9], GRA3 (Wh6 allele) can additionally trigger PERK-dependent ER-stress apoptosis in neuronal cells when overexpressed [#12].\",\n  \"teleology\": [\n    {\n      \"year\": 1993,\n      \"claim\": \"Established when and where GRA3 is delivered to the host interface, showing dense granule discharge occurs at the apical pole within minutes of invasion and deposits GRA3 at the nascent PVM.\",\n      \"evidence\": \"IFA, immunoelectron microscopy, and freeze-fracture at defined post-invasion time points in T. gondii\",\n      \"pmids\": [\"8415546\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the biochemical mechanism of membrane insertion\", \"Did not identify host partners at the PVM\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"Answered how a soluble dense granule protein becomes membrane-associated, showing GRA3 inserts directly into the vacuole membrane as a self-associating oligomer via hydrophobic interactions rather than through a stable partner complex.\",\n      \"evidence\": \"Sucrose flotation, Triton X-114 partitioning, carbonate extraction, and chemical cross-linking in T. gondii\",\n      \"pmids\": [\"8195173\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Sequence used was later shown to be a chimera\", \"Topology and orientation of the inserted protein not resolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"Defined the molecular architecture by cloning GRA3 cDNA and demonstrating an N-terminal signal sequence sufficient for dense granule/PV targeting, though the original sequence carried an error.\",\n      \"evidence\": \"cDNA cloning, in vitro translation with dog pancreas microsomes, IFA, Southern/Northern blot in T. gondii\",\n      \"pmids\": [\"7739670\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Reported sequence and MW later corrected\", \"Function beyond localization not addressed\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1995,\n      \"claim\": \"Established stage-specific expression, showing GRA3 is absent from sporozoites and appears at tachyzoite conversion, tying its function to the replicative intracellular stage.\",\n      \"evidence\": \"IFA and Western blot time course in sporozoite-infected cells in T. gondii\",\n      \"pmids\": [\"8720177\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Regulatory basis of stage-specific expression not addressed\", \"Sporozoite-stage functional consequence not tested\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Defined the secretion pathway, showing GRA3 release is constitutive, calcium-independent, and dependent on NSF/SNAP/SNARE/Rab machinery.\",\n      \"evidence\": \"Endogenous secretion assay in SLO-permeabilized parasites with recombinant NSF/\\u03b1-SNAP and inhibitors (NEM, Rab-GDI) in T. gondii\",\n      \"pmids\": [\"9891012\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific SNARE/Rab identities not defined\", \"Trigger coupling secretion to invasion not resolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Corrected the primary structure, establishing authentic GRA3 as a 24 kDa protein with signal sequence, transmembrane domain, and a C-terminal dilysine ER-retrieval motif consistent with PVM insertion.\",\n      \"evidence\": \"Sequence analysis, recombinant antibody, GFP targeting, and ESA immunoblot in T. gondii\",\n      \"pmids\": [\"16149193\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional role of the KKXX motif not experimentally tested\", \"Host-facing versus lumenal domain topology unresolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Delineated GRA3's oligomeric behavior relative to other GRA proteins, showing it co-purifies with soluble GRA2/GRA6/GRA7 complexes but dissociates from GRA2 after membrane insertion.\",\n      \"evidence\": \"HA-FLAG affinity purification from complemented KO parasites with MS in T. gondii\",\n      \"pmids\": [\"17959262\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether GRA3 forms independent oligomers versus mixed complexes in the membrane unresolved\", \"Stoichiometry not defined\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Provided the first genetic test of function, showing GRA3 is dispensable for in vitro growth and bradyzoite formation but contributes to acute virulence in vivo, restorable by complementation.\",\n      \"evidence\": \"Homologous-recombination KO with complementation and mouse survival in a type II strain of T. gondii\",\n      \"pmids\": [\"17418907\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism of virulence contribution not identified\", \"Host pathways affected not defined\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"type II\"}]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Identified the first host-cell partner, showing PVM-inserted GRA3 binds the host ER protein CAMLG, providing a molecular basis for ER recruitment to the PVM.\",\n      \"evidence\": \"Yeast two-hybrid, GST pull-down, co-IP, and co-localization in infected cells for T. gondii\",\n      \"pmids\": [\"19127325\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of ER recruitment for the parasite not tested\", \"Interaction not validated in a knockout background\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Placed GRA3 within cytosolic strand-like extensions of the PVM alongside GRA1, GRA7, and rhoptry proteins, extending its localization beyond the vacuole membrane proper.\",\n      \"evidence\": \"Multi-protein co-labeling IFA at defined time points in T. gondii\",\n      \"pmids\": [\"18809661\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional role of GRA3 in strand structures not defined\", \"Fixed-cell co-localization only\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Distinguished GRA3 from IRG-modulating effectors by showing it is dispensable for the antitumor immunity induced by uracil-auxotroph vaccines, unlike GRA2/GRA12/GRA24 and several ROPs.\",\n      \"evidence\": \"Targeted deletion in \\u0394ku80 vaccine strain with ovarian tumor model and immune readouts in type I T. gondii\",\n      \"pmids\": [\"27447180\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Does not exclude a role in other immune contexts\", \"Negative result in a specific vaccine setting only\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"type I \\u0394ku80\"}]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Revealed GRA3's role in host Golgi hijacking, showing it binds Golgi membranes, oligomerizes, and promotes Golgi tubulation and engulfment into the PV while dysregulating anterograde transport.\",\n      \"evidence\": \"Gene disruption with live host-Golgi imaging and direct Golgi membrane binding assays in T. gondii\",\n      \"pmids\": [\"30814066\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct GRA3 receptor on Golgi not identified\", \"Parasite benefit of Golgi engulfment not quantified\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Established a chronic-stage requirement, showing GRA3 deletion in the Pru type II strain severely impairs in vivo cyst development while sparing growth and in vitro differentiation.\",\n      \"evidence\": \"Targeted deletion with in vivo cyst burden and in vitro bradyzoite assays in Pru type II T. gondii\",\n      \"pmids\": [\"31266861\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of the cyst defect not defined\", \"Whether the defect is intrinsic or immune-driven unresolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"Prugniaud (Pru) type II\"}]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identified GRA3 as a cyst-wall component, linking its PVM/interface role to the chronic-stage structure.\",\n      \"evidence\": \"Percoll-enriched cyst wall fragments with CST1 IP and LC-MS/MS in T. gondii\",\n      \"pmids\": [\"31040239\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional contribution to cyst wall integrity not tested\", \"Association versus structural role not distinguished\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Defined an immune-evasion function, showing GRA3 suppresses MHC-I presentation of PV antigens to CD8+ T cells independently of IFN-\\u03b3/IRG effectors.\",\n      \"evidence\": \"GRA3 deletion with MHC-I antigen presentation assays in macrophages and dendritic cells \\u00b1IFN-\\u03b3 in type II T. gondii\",\n      \"pmids\": [\"31555296\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular mechanism of antigen presentation suppression not identified\", \"Relevant host trafficking step not defined\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"type II\"}]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Uncovered a host-cell-death consequence, showing overexpressed GRA3 (Wh6 allele) triggers PERK-dependent ER-stress apoptosis in neuronal cells.\",\n      \"evidence\": \"Overexpression in N2a cells with ER-stress/apoptosis marker immunoblotting and PERK/caspase-12 inhibitors in Chinese 1 Wh6 T. gondii\",\n      \"pmids\": [\"35918751\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Demonstrated by overexpression rather than in infection\", \"Allele-specificity versus general GRA3 effect not resolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"Chinese 1 Wh6\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Linked GRA3 to CD8+ T-cell resistance during chronic infection, showing GRA3-deficient cysts are more efficiently eliminated by perforin-dependent CD8+ T cells and that persisting cysts are enriched for GRA3 mRNA.\",\n      \"evidence\": \"GRA3-deficient strain with in vivo cyst burden under CD8+ immunity and qRT-PCR correlation in BALB/c mice with T. gondii\",\n      \"pmids\": [\"37868957\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal versus correlative role of GRA3 mRNA in persistence not resolved\", \"Link to MHC-I suppression mechanism not directly tested\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Confirmed GRA3's contribution to replication and virulence with CRISPR deletion, showing ME49\\u0394gra3 has reduced plaque formation, smaller PVs, and increased host mortality.\",\n      \"evidence\": \"CRISPR/Cas9 disruption with Western validation, plaque and PV-size assays, and mouse survival in ME49 T. gondii\",\n      \"pmids\": [\"40730529\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Increased mortality mechanism not dissected\", \"Molecular pathway linking GRA3 to replication not defined here\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"ME49\"}]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Identified a signaling mechanism for GRA3-driven proliferation, showing GRA3 binds host STING to promote STING oligomerization, IRF3 nuclear translocation, and STAT6 phosphorylation, with proliferation mediated by ISG56 and STAT6 rather than IFN-\\u03b2.\",\n      \"evidence\": \"Co-IP, STING oligomerization and nuclear fractionation assays, KO/overexpression, and ISG56/STAT6 KO/inhibitor proliferation assays in ME49 T. gondii\",\n      \"pmids\": [\"41712610\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct binding interface with STING not mapped\", \"How PVM-restricted GRA3 accesses host STING not resolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"ME49\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How GRA3's single membrane insertion domain simultaneously coordinates ER (CAMLG), Golgi, and STING engagement, and whether these interactions are physically or temporally partitioned, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of GRA3 at the PVM\", \"Topology dictating which domains face the host cytosol undefined\", \"Mechanistic link between host-organelle capture, immune evasion, and cyst persistence not integrated\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0042803\", \"supporting_discovery_ids\": [0, 11], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0005515\", \"supporting_discovery_ids\": [7, 11, 15], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0020003\", \"supporting_discovery_ids\": [0, 1, 2], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0033644\", \"supporting_discovery_ids\": [0, 1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0020026\", \"supporting_discovery_ids\": [0, 2, 3], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0006888\", \"supporting_discovery_ids\": [11], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0002479\", \"supporting_discovery_ids\": [18], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"type II\"}]},\n      {\"term_id\": \"GO:0032481\", \"supporting_discovery_ids\": [15], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"ME49\"}]},\n      {\"term_id\": \"GO:0036500\", \"supporting_discovery_ids\": [12], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"Chinese 1 Wh6\"}]}\n    ],\n    \"complexes\": [\n      \"Homo-oligomeric GRA3 assembly in the PVM (self-cross-linking)\",\n      \"Soluble GRA2/GRA3/GRA6/GRA7 co-purifying complex prior to membrane insertion\"\n    ],\n    \"partners\": [\n      \"CAMLG (host ER type II transmembrane protein)\",\n      \"Host Golgi membranes\",\n      \"Host STING\",\n      \"GRA2, GRA6, GRA7 (soluble complex, pre-insertion)\",\n      \"NSF / \\u03b1-SNAP / SNARE / Rab (secretion machinery)\"\n    ],\n    \"other_free_text\": [\n      \"24 kDa type I transmembrane dense granule protein with N-terminal signal sequence and C-terminal dilysine (KKXX) ER-retrieval motif [#4]\",\n      \"Originally published sequence was a chimera; authentic protein defined in 2005 [#4]\",\n      \"Expressed in tachyzoites but absent from sporozoites, appearing at tachyzoite conversion [#9]\",\n      \"Component of the in vitro cyst wall proteome [#17]\",\n      \"Dispensable for in vitro growth/differentiation but required for chronic cyst persistence and contributes to acute virulence [#6, #10, #16]\",\n      \"GRA3 mRNA levels correlate with cyst persistence under CD8+ T-cell immunity [#13]\",\n      \"Not required for uracil-auxotroph vaccine antitumor immunity, unlike several other GRA/ROP effectors [#14]\"\n    ]\n  },\n  \"strain_conflicts\": []\n}","audit_flag":null,"strains":[{"strain":"ME49","gene_id":"TGME49_227280","name":"GRA3","product":"dense granule protein GRA3","uniprot_acc":"A0A125YY45","chromosome":"TGME49_chrX","start_pos":1047284},{"strain":"GT1","gene_id":"TGGT1_227280","name":null,"product":"dense granule protein GRA3","uniprot_acc":null,"chromosome":"TGGT1_chrX","start_pos":956231},{"strain":"RH88","gene_id":"TGRH88_046790","name":null,"product":"dense granule protein GRA3","uniprot_acc":null,"chromosome":"CM023091","start_pos":6523258},{"strain":"VEG","gene_id":"TGVEG_227280","name":null,"product":"dense granule protein GRA3","uniprot_acc":"A0A0F7V5E7","chromosome":"TGVEG_chrX","start_pos":939398}]}