{"gene":"TG_206430","gene_symbol":"FRM1","run_date":"2026-09-08T11:06:16","timeline":{"discoveries":[{"year":2010,"finding":"TgFRM1 is required for parasite motility and host cell invasion; conditional gene disruption of TgFRM1 impairs gliding motility, and expression of dominant-negative FH2 domain mutants (impaired in actin binding but able to dimerize with endogenous formin) revealed non-redundant, critical roles for FRM1 and FRM2 individually and jointly in invasion, establishing FRM1 as an actin nucleator during host cell invasion.","method":"Conditional gene disruption (TetO/TetR system) and dominant-negative FH2 domain mutants fused to destabilization domain (DD-FKBP) for conditional expression","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional KO plus dominant-negative approach with multiple orthogonal readouts (motility, invasion assays), replicated across both formins","pmids":["20949068"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2012,"finding":"The FH1-FH2 domains of TgFRM1 dramatically enhance TgACTI (T. gondii actin I) polymerization in vitro in the absence of profilin, making TgFRM1 the primary actin nucleator for parasite actin. TgFRM1-FH1-FH2 also induces bundling of TgACTI filaments. Notably, TgFRM1 does not require TgPRF (profilin) for nucleation or bundling activities, and TgPRF actually sequesters TgACTI monomers and inhibits polymerization even in the presence of formins.","method":"In vitro actin polymerization assays using purified FH1-FH2 domains of TgFRM1 and TgFRM2 with TgACTI; profilin sequestration assays","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro biochemical reconstitution with purified proteins, multiple assay types (nucleation, bundling, sequestration), rigorous controls","pmids":["22397711"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2019,"finding":"FRM1 localizes to the conoid (apical tip) and initiates a flux of F-actin that is crucial for motility, invasion, and egress. This actin flux depends on myosins A and H and is controlled by phosphorylation via PKG and CDPK1, and by methylation via AKMT (apical lysine methyltransferase). The flux is independent of microneme secretion and persists in the absence of the glideosome-associated connector (GAC).","method":"F-actin chromobody reporters combined with gene disruption of FRM1, FRM2, FRM3, myosin A, myosin H, PKG, CDPK1, AKMT, and GAC; live imaging","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis panel with F-actin live imaging across multiple gene disruptions, defining pathway position and upstream regulators","pmids":["30753127"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2025,"finding":"CGP (a preconoidal ring protein) is required to anchor FRM1 to mature preconoidal rings (PCRs); depletion of CGP results in loss of FRM1 from PCRs in mature parasites (while initial assembly in daughter cells is unaffected), demonstrating that FRM1's apical localization depends on CGP-mediated anchoring to the PCR scaffold.","method":"Conditional depletion of CGP, immunofluorescence for FRM1 localization, cryo-electron tomography of CGP-depleted parasites","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Moderate — conditional depletion with cryo-ET structural validation and immunolocalization, multiple orthogonal methods in one study","pmids":["41315181"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2025,"finding":"FRM1 is complexed with AKMT (a protein methyltransferase) that stabilizes FRM1 from degradation and positions it at the cell apex. FRM1 contains a conserved intramolecular autoinhibitory switch: two regulatory elements upstream of the FH2 domain mediate autoinhibition; repositioning these elements via an intramolecular switch relieves autoinhibition and activates actin polymerization by the FH2 domain. This regulatory mechanism is functionally conserved in Plasmodium and other apicomplexan parasites.","method":"Structural modeling, biochemical assays (in vitro actin polymerization with regulatory domain constructs), co-immunoprecipitation/interaction studies with AKMT, mass spectrometry","journal":"Science advances","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — structural modeling combined with in vitro biochemical assays defining autoinhibitory mechanism, plus interaction studies with AKMT; single lab but multiple orthogonal methods","pmids":["41370370"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2025,"finding":"Cryo-EM analysis of the Toxoplasma conoid identified FRM1 at the preconoidal ring, pinpointing this site as the location of actin polymerization initiation and the starting point for actin translocation flux during gliding motility.","method":"Cryo-electron microscopy structural determination of conoid complexes; genetic disruption studies of conoid proteins","journal":"Nature structural & molecular biology","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — cryo-EM structural data for the complex, but FRM1-specific mechanistic detail is inferred from structural context rather than direct mutagenesis of FRM1 in this study","pmids":["41366525"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"current_model":"TgFRM1 is an apical formin that localizes to the preconoidal ring via CGP-mediated anchoring and AKMT-mediated stabilization; it is autoinhibited by intramolecular regulatory elements upstream of the FH2 domain, and activation via an intramolecular switch allows the FH2 domain to nucleate and polymerize TgACTI filaments (independently of profilin), initiating an apical-to-posterior F-actin flux that is controlled by PKG/CDPK1 phosphorylation and AKMT methylation, and that drives myosin A- and H-dependent gliding motility, host cell invasion, and egress."},"narrative":{"mechanistic_narrative":"TgFRM1 is an apical formin that serves as the primary actin nucleator driving Toxoplasma gondii gliding motility, host cell invasion, and egress [PMID:20949068, PMID:30753127]. Its FH1-FH2 domains nucleate and polymerize TgACTI filaments and bundle the resulting filaments in vitro, doing so independently of profilin—indeed TgPRF sequesters actin monomers and opposes polymerization—establishing FRM1 as the dominant nucleator for parasite actin [PMID:22397711]. FRM1 localizes to the conoid at the parasite apex, where it initiates an apical-to-posterior F-actin flux that depends on myosins A and H and is controlled by PKG- and CDPK1-mediated phosphorylation and AKMT-mediated methylation [PMID:30753127, PMID:41366525]. Its apical positioning is achieved by two mechanisms: anchoring to the mature preconoidal ring scaffold via the CGP protein, and complex formation with the methyltransferase AKMT, which stabilizes FRM1 against degradation and positions it at the apex [PMID:41315181, PMID:41370370]. FRM1 activity is gated by a conserved intramolecular autoinhibitory switch in which two regulatory elements upstream of the FH2 domain suppress polymerization until an intramolecular repositioning relieves autoinhibition, a mechanism conserved across apicomplexan parasites [PMID:41370370].","teleology":[{"year":2010,"claim":"Established that FRM1 is functionally required for the actin-dependent processes of parasite motility and invasion, moving it from a candidate to a validated nucleator in vivo.","evidence":"Conditional gene disruption (TetO/TetR) and dominant-negative FH2 domain mutants in T. gondii, scored by gliding and invasion assays","pmids":["20949068"],"confidence":"High","gaps":["Did not demonstrate direct actin nucleation biochemically","Did not resolve subcellular site of FRM1 action","Individual vs joint roles of FRM1 and FRM2 not fully separated"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2012,"claim":"Reconstitution with purified proteins showed FRM1 directly nucleates and bundles TgACTI without profilin, resolving how parasite actin polymerizes and revealing that profilin acts as a sequestering inhibitor rather than a formin cofactor.","evidence":"In vitro actin polymerization and sequestration assays with purified TgFRM1 FH1-FH2 domains, TgACTI, and TgPRF","pmids":["22397711"],"confidence":"High","gaps":["In vitro activity of isolated FH1-FH2 does not address in vivo regulation of full-length protein","Did not address how nucleation is spatially restricted","Physiological role of profilin sequestration unresolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2019,"claim":"Live F-actin imaging with a genetic epistasis panel placed FRM1 at the conoid as the initiator of a directional F-actin flux and identified myosins A/H, PKG, CDPK1, and AKMT as the effectors and regulators, defining the pathway context of FRM1 activity.","evidence":"F-actin chromobody reporters and live imaging across gene disruptions of FRM1/2/3, myosin A/H, PKG, CDPK1, AKMT, and GAC in T. gondii","pmids":["30753127"],"confidence":"High","gaps":["Did not identify the physical anchor for FRM1 at the apex","Molecular mechanism of phosphorylation/methylation control on FRM1 not defined","Direction of causality between regulators and FRM1 not molecularly resolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2025,"claim":"Identified CGP as the preconoidal ring anchor for FRM1, explaining how the nucleator is retained at the apex in mature parasites versus during daughter assembly.","evidence":"Conditional CGP depletion with FRM1 immunofluorescence and cryo-electron tomography in T. gondii","pmids":["41315181"],"confidence":"High","gaps":["Direct physical interaction between CGP and FRM1 not established","Why initial daughter-cell assembly is CGP-independent unresolved","Does not address activation state of anchored FRM1"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2025,"claim":"Defined a conserved intramolecular autoinhibitory switch upstream of the FH2 domain and showed AKMT complexes with FRM1 to stabilize and position it, explaining how nucleation is kept off until activation and how the protein is protected from degradation.","evidence":"Structural modeling, in vitro polymerization with regulatory-domain constructs, and AKMT co-IP/mass spectrometry in T. gondii, with conservation noted in Plasmodium","pmids":["41370370"],"confidence":"High","gaps":["The in vivo trigger that flips the intramolecular switch is not identified","Link between AKMT methylation activity and switch relief not mechanistically resolved","Structural model not experimentally solved at high resolution"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2025,"claim":"Cryo-EM localization of FRM1 to the preconoidal ring pinpointed this site as the physical origin of actin polymerization and the starting point of the translocation flux.","evidence":"Cryo-electron microscopy of conoid complexes with conoid protein disruption studies in T. gondii","pmids":["41366525"],"confidence":"Medium","gaps":["FRM1-specific mechanistic role inferred from structural context rather than direct FRM1 mutagenesis in this study","Does not resolve activation state of FRM1 within the ring","Does not connect structure to phosphoregulation"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":null,"claim":"The in vivo signal that relieves FRM1 autoinhibition and the mechanistic link between PKG/CDPK1 phosphorylation, AKMT methylation, CGP anchoring, and switch activation remain unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No demonstrated molecular trigger for the intramolecular switch in vivo","Phosphorylation and methylation sites on FRM1 and their functional consequences not mapped","Direct FRM1-CGP and FRM1-AKMT interaction interfaces not structurally defined"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["FRM1-AKMT complex [#4]"],"partners":["TGACTI (ACTIN SUBSTRATE) [#1]","AKMT (APICAL LYSINE METHYLTRANSFERASE; STABILIZER AND POSITIONER) [#2, #4]","CGP (PRECONOIDAL RING ANCHOR) [#3]","PKG (PHOSPHOREGULATOR OF ACTIN FLUX) [#2]","CDPK1 (PHOSPHOREGULATOR OF ACTIN FLUX) [#2]","MYOSIN A (FLUX EFFECTOR) [#2]","MYOSIN H (FLUX EFFECTOR) [#2]"],"other_free_text":["TgPRF (profilin) sequesters TgACTI monomers and inhibits polymerization, opposing rather than assisting FRM1 [#1].","FRM1 contains an intramolecular autoinhibitory switch with two regulatory elements upstream of the FH2 domain; this regulatory architecture is conserved in Plasmodium and other apicomplexans [#4].","FRM1 acts non-redundantly with FRM2 in invasion; both are individually and jointly required [#0]."]},"strain_conflicts":[]},"prefetch_data":{},"corpus_meta":[{"pmid":"30753127","id":"PMC_30753127","title":"Three F-actin assembly centers regulate organelle inheritance, cell-cell communication and motility in Toxoplasma gondii.","date":"2019","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/30753127","citation_count":68,"is_preprint":false},{"pmid":"20949068","id":"PMC_20949068","title":"Concerted action of two formins in gliding motility and host cell invasion by Toxoplasma gondii.","date":"2010","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/20949068","citation_count":67,"is_preprint":false},{"pmid":"22397711","id":"PMC_22397711","title":"Toxoplasma gondii profilin acts primarily to sequester G-actin while formins efficiently nucleate actin filament formation in vitro.","date":"2012","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22397711","citation_count":37,"is_preprint":false},{"pmid":"41366525","id":"PMC_41366525","title":"Atomic models of the Toxoplasma cell invasion machinery.","date":"2025","source":"Nature structural & molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/41366525","citation_count":7,"is_preprint":false},{"pmid":"41315181","id":"PMC_41315181","title":"An apical ring protein essential for conoid complex assembly and daughter cell formation in Toxoplasma gondii.","date":"2025","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/41315181","citation_count":4,"is_preprint":false},{"pmid":"41370370","id":"PMC_41370370","title":"Evolutionarily convergent mechanism of formin regulation coordinates actin polymerization in apicomplexan parasites.","date":"2025","source":"Science advances","url":"https://pubmed.ncbi.nlm.nih.gov/41370370","citation_count":2,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":4828,"output_tokens":1955,"usd":0.021905,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":7172,"output_tokens":3368,"usd":0.06003,"stage2_stop_reason":"end_turn"},"total_usd":0.081935,"stage1_batch_id":"msgbatch_01WokvBYTB6JLnYrpD4rXnyV","stage2_batch_id":"msgbatch_01M7hsQDvz6AqVC9DLVjQzzc","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2010,\n      \"finding\": \"TgFRM1 is required for parasite motility and host cell invasion; conditional gene disruption of TgFRM1 impairs gliding motility, and expression of dominant-negative FH2 domain mutants (impaired in actin binding but able to dimerize with endogenous formin) revealed non-redundant, critical roles for FRM1 and FRM2 individually and jointly in invasion, establishing FRM1 as an actin nucleator during host cell invasion.\",\n      \"method\": \"Conditional gene disruption (TetO/TetR system) and dominant-negative FH2 domain mutants fused to destabilization domain (DD-FKBP) for conditional expression\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional KO plus dominant-negative approach with multiple orthogonal readouts (motility, invasion assays), replicated across both formins\",\n      \"pmids\": [\"20949068\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The FH1-FH2 domains of TgFRM1 dramatically enhance TgACTI (T. gondii actin I) polymerization in vitro in the absence of profilin, making TgFRM1 the primary actin nucleator for parasite actin. TgFRM1-FH1-FH2 also induces bundling of TgACTI filaments. Notably, TgFRM1 does not require TgPRF (profilin) for nucleation or bundling activities, and TgPRF actually sequesters TgACTI monomers and inhibits polymerization even in the presence of formins.\",\n      \"method\": \"In vitro actin polymerization assays using purified FH1-FH2 domains of TgFRM1 and TgFRM2 with TgACTI; profilin sequestration assays\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro biochemical reconstitution with purified proteins, multiple assay types (nucleation, bundling, sequestration), rigorous controls\",\n      \"pmids\": [\"22397711\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"FRM1 localizes to the conoid (apical tip) and initiates a flux of F-actin that is crucial for motility, invasion, and egress. This actin flux depends on myosins A and H and is controlled by phosphorylation via PKG and CDPK1, and by methylation via AKMT (apical lysine methyltransferase). The flux is independent of microneme secretion and persists in the absence of the glideosome-associated connector (GAC).\",\n      \"method\": \"F-actin chromobody reporters combined with gene disruption of FRM1, FRM2, FRM3, myosin A, myosin H, PKG, CDPK1, AKMT, and GAC; live imaging\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis panel with F-actin live imaging across multiple gene disruptions, defining pathway position and upstream regulators\",\n      \"pmids\": [\"30753127\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CGP (a preconoidal ring protein) is required to anchor FRM1 to mature preconoidal rings (PCRs); depletion of CGP results in loss of FRM1 from PCRs in mature parasites (while initial assembly in daughter cells is unaffected), demonstrating that FRM1's apical localization depends on CGP-mediated anchoring to the PCR scaffold.\",\n      \"method\": \"Conditional depletion of CGP, immunofluorescence for FRM1 localization, cryo-electron tomography of CGP-depleted parasites\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional depletion with cryo-ET structural validation and immunolocalization, multiple orthogonal methods in one study\",\n      \"pmids\": [\"41315181\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"FRM1 is complexed with AKMT (a protein methyltransferase) that stabilizes FRM1 from degradation and positions it at the cell apex. FRM1 contains a conserved intramolecular autoinhibitory switch: two regulatory elements upstream of the FH2 domain mediate autoinhibition; repositioning these elements via an intramolecular switch relieves autoinhibition and activates actin polymerization by the FH2 domain. This regulatory mechanism is functionally conserved in Plasmodium and other apicomplexan parasites.\",\n      \"method\": \"Structural modeling, biochemical assays (in vitro actin polymerization with regulatory domain constructs), co-immunoprecipitation/interaction studies with AKMT, mass spectrometry\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — structural modeling combined with in vitro biochemical assays defining autoinhibitory mechanism, plus interaction studies with AKMT; single lab but multiple orthogonal methods\",\n      \"pmids\": [\"41370370\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Cryo-EM analysis of the Toxoplasma conoid identified FRM1 at the preconoidal ring, pinpointing this site as the location of actin polymerization initiation and the starting point for actin translocation flux during gliding motility.\",\n      \"method\": \"Cryo-electron microscopy structural determination of conoid complexes; genetic disruption studies of conoid proteins\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — cryo-EM structural data for the complex, but FRM1-specific mechanistic detail is inferred from structural context rather than direct mutagenesis of FRM1 in this study\",\n      \"pmids\": [\"41366525\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"TgFRM1 is an apical formin that localizes to the preconoidal ring via CGP-mediated anchoring and AKMT-mediated stabilization; it is autoinhibited by intramolecular regulatory elements upstream of the FH2 domain, and activation via an intramolecular switch allows the FH2 domain to nucleate and polymerize TgACTI filaments (independently of profilin), initiating an apical-to-posterior F-actin flux that is controlled by PKG/CDPK1 phosphorylation and AKMT methylation, and that drives myosin A- and H-dependent gliding motility, host cell invasion, and egress.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TgFRM1 is an apical formin that serves as the primary actin nucleator driving Toxoplasma gondii gliding motility, host cell invasion, and egress [#0, #2]. Its FH1-FH2 domains nucleate and polymerize TgACTI filaments and bundle the resulting filaments in vitro, doing so independently of profilin—indeed TgPRF sequesters actin monomers and opposes polymerization—establishing FRM1 as the dominant nucleator for parasite actin [#1]. FRM1 localizes to the conoid at the parasite apex, where it initiates an apical-to-posterior F-actin flux that depends on myosins A and H and is controlled by PKG- and CDPK1-mediated phosphorylation and AKMT-mediated methylation [#2, #5]. Its apical positioning is achieved by two mechanisms: anchoring to the mature preconoidal ring scaffold via the CGP protein, and complex formation with the methyltransferase AKMT, which stabilizes FRM1 against degradation and positions it at the apex [#3, #4]. FRM1 activity is gated by a conserved intramolecular autoinhibitory switch in which two regulatory elements upstream of the FH2 domain suppress polymerization until an intramolecular repositioning relieves autoinhibition, a mechanism conserved across apicomplexan parasites [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 2010,\n      \"claim\": \"Established that FRM1 is functionally required for the actin-dependent processes of parasite motility and invasion, moving it from a candidate to a validated nucleator in vivo.\",\n      \"evidence\": \"Conditional gene disruption (TetO/TetR) and dominant-negative FH2 domain mutants in T. gondii, scored by gliding and invasion assays\",\n      \"pmids\": [\"20949068\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not demonstrate direct actin nucleation biochemically\", \"Did not resolve subcellular site of FRM1 action\", \"Individual vs joint roles of FRM1 and FRM2 not fully separated\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Reconstitution with purified proteins showed FRM1 directly nucleates and bundles TgACTI without profilin, resolving how parasite actin polymerizes and revealing that profilin acts as a sequestering inhibitor rather than a formin cofactor.\",\n      \"evidence\": \"In vitro actin polymerization and sequestration assays with purified TgFRM1 FH1-FH2 domains, TgACTI, and TgPRF\",\n      \"pmids\": [\"22397711\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vitro activity of isolated FH1-FH2 does not address in vivo regulation of full-length protein\", \"Did not address how nucleation is spatially restricted\", \"Physiological role of profilin sequestration unresolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Live F-actin imaging with a genetic epistasis panel placed FRM1 at the conoid as the initiator of a directional F-actin flux and identified myosins A/H, PKG, CDPK1, and AKMT as the effectors and regulators, defining the pathway context of FRM1 activity.\",\n      \"evidence\": \"F-actin chromobody reporters and live imaging across gene disruptions of FRM1/2/3, myosin A/H, PKG, CDPK1, AKMT, and GAC in T. gondii\",\n      \"pmids\": [\"30753127\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the physical anchor for FRM1 at the apex\", \"Molecular mechanism of phosphorylation/methylation control on FRM1 not defined\", \"Direction of causality between regulators and FRM1 not molecularly resolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified CGP as the preconoidal ring anchor for FRM1, explaining how the nucleator is retained at the apex in mature parasites versus during daughter assembly.\",\n      \"evidence\": \"Conditional CGP depletion with FRM1 immunofluorescence and cryo-electron tomography in T. gondii\",\n      \"pmids\": [\"41315181\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct physical interaction between CGP and FRM1 not established\", \"Why initial daughter-cell assembly is CGP-independent unresolved\", \"Does not address activation state of anchored FRM1\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined a conserved intramolecular autoinhibitory switch upstream of the FH2 domain and showed AKMT complexes with FRM1 to stabilize and position it, explaining how nucleation is kept off until activation and how the protein is protected from degradation.\",\n      \"evidence\": \"Structural modeling, in vitro polymerization with regulatory-domain constructs, and AKMT co-IP/mass spectrometry in T. gondii, with conservation noted in Plasmodium\",\n      \"pmids\": [\"41370370\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The in vivo trigger that flips the intramolecular switch is not identified\", \"Link between AKMT methylation activity and switch relief not mechanistically resolved\", \"Structural model not experimentally solved at high resolution\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Cryo-EM localization of FRM1 to the preconoidal ring pinpointed this site as the physical origin of actin polymerization and the starting point of the translocation flux.\",\n      \"evidence\": \"Cryo-electron microscopy of conoid complexes with conoid protein disruption studies in T. gondii\",\n      \"pmids\": [\"41366525\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"FRM1-specific mechanistic role inferred from structural context rather than direct FRM1 mutagenesis in this study\", \"Does not resolve activation state of FRM1 within the ring\", \"Does not connect structure to phosphoregulation\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The in vivo signal that relieves FRM1 autoinhibition and the mechanistic link between PKG/CDPK1 phosphorylation, AKMT methylation, CGP anchoring, and switch activation remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No demonstrated molecular trigger for the intramolecular switch in vivo\", \"Phosphorylation and methylation sites on FRM1 and their functional consequences not mapped\", \"Direct FRM1-CGP and FRM1-AKMT interaction interfaces not structurally defined\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003785\", \"supporting_discovery_ids\": [1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0051015\", \"supporting_discovery_ids\": [1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0051017\", \"supporting_discovery_ids\": [1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0020009\", \"supporting_discovery_ids\": [2, 3, 5], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0071965\", \"supporting_discovery_ids\": [0, 2], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0030041\", \"supporting_discovery_ids\": [1, 2], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"complexes\": [\n      \"FRM1-AKMT complex [#4]\"\n    ],\n    \"partners\": [\n      \"TgACTI (actin substrate) [#1]\",\n      \"AKMT (apical lysine methyltransferase; stabilizer and positioner) [#2, #4]\",\n      \"CGP (preconoidal ring anchor) [#3]\",\n      \"PKG (phosphoregulator of actin flux) [#2]\",\n      \"CDPK1 (phosphoregulator of actin flux) [#2]\",\n      \"Myosin A (flux effector) [#2]\",\n      \"Myosin H (flux effector) [#2]\"\n    ],\n    \"other_free_text\": [\n      \"TgPRF (profilin) sequesters TgACTI monomers and inhibits polymerization, opposing rather than assisting FRM1 [#1].\",\n      \"FRM1 contains an intramolecular autoinhibitory switch with two regulatory elements upstream of the FH2 domain; this regulatory architecture is conserved in Plasmodium and other apicomplexans [#4].\",\n      \"FRM1 acts non-redundantly with FRM2 in invasion; both are individually and jointly required [#0].\"\n    ]\n  },\n  \"strain_conflicts\": []\n}","audit_flag":null,"strains":[{"strain":"ME49","gene_id":"TGME49_206430","name":"FRM1","product":"formin FRM1","uniprot_acc":"S8F5G6","chromosome":"TGME49_chrVIIa","start_pos":973325},{"strain":"GT1","gene_id":"TGGT1_206430","name":null,"product":"formin FRM1","uniprot_acc":null,"chromosome":"TGGT1_chrVIIa","start_pos":965469},{"strain":"RH88","gene_id":"TGRH88_033580","name":null,"product":"formin FRM1","uniprot_acc":null,"chromosome":"CM023088","start_pos":1053572},{"strain":"VEG","gene_id":"TGVEG_206430","name":null,"product":"formin FRM1","uniprot_acc":"V4YZ27","chromosome":"TGVEG_chrVIIa","start_pos":1030212}]}