{"gene":"TG_249670","gene_symbol":"","run_date":"2026-09-08T12:58:25","timeline":{"discoveries":[{"year":2002,"finding":"T. gondii cathepsin B (toxopain-1/TgCPB) was cloned as a single-copy gene (tgcp1), refolded recombinant enzyme was active, and substrate specificity plus homology modeling confirmed cathepsin B identity. The enzyme localizes to rhoptries (secretory organelles required for invasion), and cathepsin B inhibitors delayed processing of the pro-rhoptry protein 2 to mature rhoptry proteins. Specific cathepsin B inhibitors also interrupted tachyzoite invasion of host cells and caused small, poorly developed rhoptries.","method":"Gene cloning, recombinant protein refolding, substrate specificity assay, homology modeling, immunolocalization to rhoptries, pulse-chase immunoprecipitation with cathepsin B inhibitor, dominant-negative micro1-adaptin expression, inhibitor treatment of infected fibroblasts","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — multiple orthogonal methods (recombinant enzyme activity, substrate profiling, homology modeling, immunolocalization, pulse-chase, genetic dominant-negative, pharmacological inhibition) in a single focused study","pmids":["12000756"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2004,"finding":"Antisense knockdown of toxopain-1 (TgCPB) mRNA and protein by >60% significantly decreased parasite invasion and multiplication in vitro, validating its functional requirement for parasite growth.","method":"Antisense knockdown of toxopain-1 mRNA/protein, in vitro invasion and multiplication assays, in vivo chicken embryo congenital toxoplasmosis model","journal":"Infection and immunity","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic knockdown with quantified phenotypic readouts in vitro and in vivo, single lab","pmids":["15102804"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2006,"finding":"TgCPB (cathepsin B) was confirmed as an endopeptidase (in contrast to the exopeptidase cathepsin C members). TgCPB mRNA was undetectable in in vivo bradyzoites.","method":"Real-time PCR expression analysis; substrate specificity classification of recombinant cathepsins","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — biochemical classification of enzymatic activity plus expression data, single lab, two methods","pmids":["17164247"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2008,"finding":"Endogenous cysteine proteinase inhibitors (ICPs/toxostatins) inhibit TgCPB in the nanomolar range. Overexpression of toxostatin-1 significantly decreased overall cysteine proteinase activity in parasite lysates, but had no detectable effect on invasion or intracellular multiplication.","method":"Gene cloning, recombinant protein expression, enzyme inhibition assays (IC50/Ki), transgenic overexpression of toxostatin-1 with invasion/multiplication readouts","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro enzyme inhibition plus transgenic overexpression phenotype, single lab","pmids":["19111576"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2012,"finding":"TgCPB does not undergo self-maturation but requires TgCPL for activation; recombinant TgCPL can partially mature TgCPB in vitro. Antibody-based localization with validated specificity placed TgCPB in the lysosome-like vacuolar compartment (VAC) together with TgCPL, contradicting the earlier rhoptry localization report. TgCPB knock-out parasites show normal rhoptry morphology and normal rhoptry protein maturation, establishing that TgCPB is not required for these processes.","method":"Recombinant enzyme maturation assay in vitro, validated antibody-based immunolocalization, TgCPB knock-out parasite analysis (rhoptry morphology, rhoptry protein processing)","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — recombinant in vitro maturation assay combined with validated antibody localization and genetic knock-out with specific phenotypic readouts; directly revises prior localization claim","pmids":["23250753"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"finding":"In T. gondii-infected human placental trophoblast and amniotic cells, TgCPB (cathepsin B) is released into the cytosol downstream of ROS production and upstream of NLRP1/NLRP3/NLRC4/AIM2 inflammasome activation and pyroptosis. Pharmacological inhibition of cathepsin B reversed inflammasome activation and pyroptosis in these cells.","method":"CatB inhibitor treatment of T. gondii-infected placental cell lines, ROS scavenger experiments, inflammasome-specific siRNA knockdown, measurement of caspase-1 cleavage, IL-1β maturation, gasdermin D cleavage","journal":"The American journal of pathology","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — pharmacological inhibition and siRNA knockdown with multiple pathway readouts in host cell context, single lab","pmids":["37741453"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"current_model":"T. gondii cathepsin B (TgCPB/toxopain-1) is an endopeptidase cysteine protease that localizes to the lysosome-like vacuolar compartment (VAC) — not the rhoptries as originally proposed — where it requires TgCPL for zymogen maturation; it contributes to parasite invasion and intracellular growth, is inhibited by endogenous toxostatins in the nanomolar range, and in infected host cells it is released into the cytosol downstream of ROS to drive NLRP1/NLRP3/NLRC4/AIM2 inflammasome activation and pyroptosis."},"narrative":{"mechanistic_narrative":"Toxoplasma gondii cathepsin B (TgCPB/toxopain-1) is a single-copy cysteine endopeptidase that supports parasite invasion and intracellular growth [PMID:12000756, PMID:15102804]. It is synthesized as a zymogen that cannot self-mature and instead depends on TgCPL for proteolytic activation, and it localizes to the lysosome-like vacuolar compartment (VAC) together with TgCPL rather than to the rhoptries proposed in the initial characterization [PMID:23250753]. Consistent with this revised localization, TgCPB knock-out parasites retain normal rhoptry morphology and rhoptry protein maturation, showing it is dispensable for those processes [PMID:23250753]. Its activity is restrained by endogenous cysteine proteinase inhibitors (toxostatins) acting in the nanomolar range [PMID:19111576]. In infected human placental cells, TgCPB is released into the host cytosol downstream of ROS to drive NLRP1/NLRP3/NLRC4/AIM2 inflammasome activation and pyroptosis [PMID:37741453].","teleology":[{"year":2002,"claim":"Establishing whether T. gondii encodes a functional cathepsin B and what it does required cloning and characterizing the enzyme; this defined TgCPB as an active cysteine protease and first linked it to invasion.","evidence":"Gene cloning, recombinant refolding with substrate profiling and homology modeling, immunolocalization, pulse-chase, and inhibitor treatment of infected fibroblasts","pmids":["12000756"],"confidence":"High","gaps":["Initial rhoptry localization was later contradicted","Inhibitor effects on invasion are pharmacological, not genetic in this study"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2004,"claim":"To move from correlation to functional requirement, antisense knockdown tested whether depleting TgCPB impairs the parasite, confirming its contribution to invasion and multiplication.","evidence":"Antisense knockdown of mRNA/protein with in vitro invasion/multiplication assays and a chicken embryo congenital toxoplasmosis model","pmids":["15102804"],"confidence":"Medium","gaps":["Incomplete (>60%) knockdown","Mechanism by which loss impairs invasion not resolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2006,"claim":"Classifying TgCPB's catalytic mode distinguished it as an endopeptidase and revealed stage-specific expression, refining its enzymatic identity relative to other parasite cathepsins.","evidence":"Substrate specificity classification of recombinant enzymes and real-time PCR expression analysis","pmids":["17164247"],"confidence":"Medium","gaps":["Physiological substrates not identified","Basis of bradyzoite silencing unknown"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2008,"claim":"Identifying endogenous regulators addressed how TgCPB activity is controlled; toxostatins inhibit it at nanomolar potency, though overexpression did not alter invasion or growth.","evidence":"Cloning and recombinant expression of ICPs/toxostatins, enzyme inhibition assays, and transgenic toxostatin-1 overexpression with phenotypic readouts","pmids":["19111576"],"confidence":"Medium","gaps":["Lack of phenotype leaves physiological role of the inhibitor unclear","Specificity of toxostatins for TgCPB versus other proteases not fully resolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2012,"claim":"Determining how TgCPB is activated and where it acts revised the field: it requires TgCPL for maturation and resides in the VAC, not the rhoptries, and is dispensable for rhoptry biogenesis.","evidence":"In vitro recombinant maturation assay, validated antibody immunolocalization, and TgCPB knock-out analysis of rhoptry morphology and protein processing","pmids":["23250753"],"confidence":"High","gaps":["VAC-resident substrates of TgCPB not defined","How TgCPB contributes to invasion/growth given VAC localization is unresolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"claim":"Extending TgCPB's relevance to host response, its release into the host cytosol was placed downstream of ROS and upstream of inflammasome-driven pyroptosis in infected placental cells.","evidence":"Cathepsin B inhibitor and ROS scavenger treatment, inflammasome-specific siRNA, and assays of caspase-1 cleavage, IL-1β maturation, and gasdermin D cleavage in infected trophoblast/amniotic cells","pmids":["37741453"],"confidence":"Medium","gaps":["Mechanism of TgCPB release into host cytosol not defined","Direct molecular link between TgCPB and each inflammasome sensor not established","Pharmacological/siRNA readouts only, single cell context"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":null,"claim":"The physiological substrates of TgCPB within the VAC and the molecular basis by which it promotes invasion and intracellular growth remain undefined.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No endogenous VAC substrate identified","Causal mechanism linking VAC localization to invasion phenotype unresolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":[],"partners":["TGCPL (CATHEPSIN L; MATURES TGCPB ZYMOGEN) [#4]","TOXOSTATINS/ICPS (ENDOGENOUS NANOMOLAR CYSTEINE PROTEINASE INHIBITORS) [#3]"],"other_free_text":["TgCPB is a single-copy gene (tgcp1) encoding an active refoldable cysteine protease [#0].","TgCPB cannot self-mature and depends on TgCPL for zymogen activation [#4].","TgCPB knock-out parasites have normal rhoptry morphology and rhoptry protein maturation, so TgCPB is dispensable for rhoptry biogenesis [#4].","TgCPB mRNA is undetectable in in vivo bradyzoites, indicating stage-specific expression [#2].","In infected host placental cells, TgCPB acts downstream of ROS and upstream of NLRP1/NLRP3/NLRC4/AIM2 inflammasome activation and pyroptosis [#5]."]},"strain_conflicts":[]},"prefetch_data":{},"corpus_meta":[{"pmid":"12000756","id":"PMC_12000756","title":"The cathepsin B of Toxoplasma gondii, toxopain-1, is critical for parasite invasion and rhoptry protein processing.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12000756","citation_count":76,"is_preprint":false},{"pmid":"17164247","id":"PMC_17164247","title":"Cathepsin Cs are key for the intracellular survival of the protozoan parasite, Toxoplasma gondii.","date":"2006","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/17164247","citation_count":46,"is_preprint":false},{"pmid":"19111576","id":"PMC_19111576","title":"The cathepsin L of Toxoplasma gondii (TgCPL) and its endogenous macromolecular inhibitor, toxostatin.","date":"2008","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/19111576","citation_count":36,"is_preprint":false},{"pmid":"21660658","id":"PMC_21660658","title":"Cathepsin proteases in Toxoplasma gondii.","date":"2011","source":"Advances in experimental medicine and biology","url":"https://pubmed.ncbi.nlm.nih.gov/21660658","citation_count":33,"is_preprint":false},{"pmid":"23250753","id":"PMC_23250753","title":"Non-canonical maturation of two papain-family proteases in Toxoplasma gondii.","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/23250753","citation_count":31,"is_preprint":false},{"pmid":"15102804","id":"PMC_15102804","title":"Toxopain-1 is critical for infection in a novel chicken embryo model of congenital toxoplasmosis.","date":"2004","source":"Infection and immunity","url":"https://pubmed.ncbi.nlm.nih.gov/15102804","citation_count":28,"is_preprint":false},{"pmid":"23651838","id":"PMC_23651838","title":"Toxoplasma gondii cathepsin proteases are undeveloped prominent vaccine antigens against toxoplasmosis.","date":"2013","source":"BMC infectious diseases","url":"https://pubmed.ncbi.nlm.nih.gov/23651838","citation_count":24,"is_preprint":false},{"pmid":"37741453","id":"PMC_37741453","title":"Toxoplasma gondii Induces Pyroptosis in Human Placental Trophoblast and Amniotic Cells by Inducing ROS Production and Activation of Cathepsin B and NLRP1/NLRP3/NLRC4/AIM2 Inflammasome.","date":"2023","source":"The American journal of pathology","url":"https://pubmed.ncbi.nlm.nih.gov/37741453","citation_count":23,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":6079,"output_tokens":1851,"usd":0.023001,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":7170,"output_tokens":2992,"usd":0.055325,"stage2_stop_reason":"end_turn"},"total_usd":0.078326,"stage1_batch_id":"msgbatch_01TEPNZ4MCzJ7xtsNwosiDRk","stage2_batch_id":"msgbatch_01FQShM7n1sfCr4pWTDShmki","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2002,\n      \"finding\": \"T. gondii cathepsin B (toxopain-1/TgCPB) was cloned as a single-copy gene (tgcp1), refolded recombinant enzyme was active, and substrate specificity plus homology modeling confirmed cathepsin B identity. The enzyme localizes to rhoptries (secretory organelles required for invasion), and cathepsin B inhibitors delayed processing of the pro-rhoptry protein 2 to mature rhoptry proteins. Specific cathepsin B inhibitors also interrupted tachyzoite invasion of host cells and caused small, poorly developed rhoptries.\",\n      \"method\": \"Gene cloning, recombinant protein refolding, substrate specificity assay, homology modeling, immunolocalization to rhoptries, pulse-chase immunoprecipitation with cathepsin B inhibitor, dominant-negative micro1-adaptin expression, inhibitor treatment of infected fibroblasts\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — multiple orthogonal methods (recombinant enzyme activity, substrate profiling, homology modeling, immunolocalization, pulse-chase, genetic dominant-negative, pharmacological inhibition) in a single focused study\",\n      \"pmids\": [\"12000756\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Antisense knockdown of toxopain-1 (TgCPB) mRNA and protein by >60% significantly decreased parasite invasion and multiplication in vitro, validating its functional requirement for parasite growth.\",\n      \"method\": \"Antisense knockdown of toxopain-1 mRNA/protein, in vitro invasion and multiplication assays, in vivo chicken embryo congenital toxoplasmosis model\",\n      \"journal\": \"Infection and immunity\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockdown with quantified phenotypic readouts in vitro and in vivo, single lab\",\n      \"pmids\": [\"15102804\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"TgCPB (cathepsin B) was confirmed as an endopeptidase (in contrast to the exopeptidase cathepsin C members). TgCPB mRNA was undetectable in in vivo bradyzoites.\",\n      \"method\": \"Real-time PCR expression analysis; substrate specificity classification of recombinant cathepsins\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — biochemical classification of enzymatic activity plus expression data, single lab, two methods\",\n      \"pmids\": [\"17164247\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Endogenous cysteine proteinase inhibitors (ICPs/toxostatins) inhibit TgCPB in the nanomolar range. Overexpression of toxostatin-1 significantly decreased overall cysteine proteinase activity in parasite lysates, but had no detectable effect on invasion or intracellular multiplication.\",\n      \"method\": \"Gene cloning, recombinant protein expression, enzyme inhibition assays (IC50/Ki), transgenic overexpression of toxostatin-1 with invasion/multiplication readouts\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro enzyme inhibition plus transgenic overexpression phenotype, single lab\",\n      \"pmids\": [\"19111576\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"TgCPB does not undergo self-maturation but requires TgCPL for activation; recombinant TgCPL can partially mature TgCPB in vitro. Antibody-based localization with validated specificity placed TgCPB in the lysosome-like vacuolar compartment (VAC) together with TgCPL, contradicting the earlier rhoptry localization report. TgCPB knock-out parasites show normal rhoptry morphology and normal rhoptry protein maturation, establishing that TgCPB is not required for these processes.\",\n      \"method\": \"Recombinant enzyme maturation assay in vitro, validated antibody-based immunolocalization, TgCPB knock-out parasite analysis (rhoptry morphology, rhoptry protein processing)\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — recombinant in vitro maturation assay combined with validated antibody localization and genetic knock-out with specific phenotypic readouts; directly revises prior localization claim\",\n      \"pmids\": [\"23250753\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In T. gondii-infected human placental trophoblast and amniotic cells, TgCPB (cathepsin B) is released into the cytosol downstream of ROS production and upstream of NLRP1/NLRP3/NLRC4/AIM2 inflammasome activation and pyroptosis. Pharmacological inhibition of cathepsin B reversed inflammasome activation and pyroptosis in these cells.\",\n      \"method\": \"CatB inhibitor treatment of T. gondii-infected placental cell lines, ROS scavenger experiments, inflammasome-specific siRNA knockdown, measurement of caspase-1 cleavage, IL-1β maturation, gasdermin D cleavage\",\n      \"journal\": \"The American journal of pathology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — pharmacological inhibition and siRNA knockdown with multiple pathway readouts in host cell context, single lab\",\n      \"pmids\": [\"37741453\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"T. gondii cathepsin B (TgCPB/toxopain-1) is an endopeptidase cysteine protease that localizes to the lysosome-like vacuolar compartment (VAC) — not the rhoptries as originally proposed — where it requires TgCPL for zymogen maturation; it contributes to parasite invasion and intracellular growth, is inhibited by endogenous toxostatins in the nanomolar range, and in infected host cells it is released into the cytosol downstream of ROS to drive NLRP1/NLRP3/NLRC4/AIM2 inflammasome activation and pyroptosis.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"Toxoplasma gondii cathepsin B (TgCPB/toxopain-1) is a single-copy cysteine endopeptidase that supports parasite invasion and intracellular growth [#0, #1]. It is synthesized as a zymogen that cannot self-mature and instead depends on TgCPL for proteolytic activation, and it localizes to the lysosome-like vacuolar compartment (VAC) together with TgCPL rather than to the rhoptries proposed in the initial characterization [#4]. Consistent with this revised localization, TgCPB knock-out parasites retain normal rhoptry morphology and rhoptry protein maturation, showing it is dispensable for those processes [#4]. Its activity is restrained by endogenous cysteine proteinase inhibitors (toxostatins) acting in the nanomolar range [#3]. In infected human placental cells, TgCPB is released into the host cytosol downstream of ROS to drive NLRP1/NLRP3/NLRC4/AIM2 inflammasome activation and pyroptosis [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Establishing whether T. gondii encodes a functional cathepsin B and what it does required cloning and characterizing the enzyme; this defined TgCPB as an active cysteine protease and first linked it to invasion.\",\n      \"evidence\": \"Gene cloning, recombinant refolding with substrate profiling and homology modeling, immunolocalization, pulse-chase, and inhibitor treatment of infected fibroblasts\",\n      \"pmids\": [\"12000756\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Initial rhoptry localization was later contradicted\", \"Inhibitor effects on invasion are pharmacological, not genetic in this study\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"To move from correlation to functional requirement, antisense knockdown tested whether depleting TgCPB impairs the parasite, confirming its contribution to invasion and multiplication.\",\n      \"evidence\": \"Antisense knockdown of mRNA/protein with in vitro invasion/multiplication assays and a chicken embryo congenital toxoplasmosis model\",\n      \"pmids\": [\"15102804\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Incomplete (>60%) knockdown\", \"Mechanism by which loss impairs invasion not resolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Classifying TgCPB's catalytic mode distinguished it as an endopeptidase and revealed stage-specific expression, refining its enzymatic identity relative to other parasite cathepsins.\",\n      \"evidence\": \"Substrate specificity classification of recombinant enzymes and real-time PCR expression analysis\",\n      \"pmids\": [\"17164247\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological substrates not identified\", \"Basis of bradyzoite silencing unknown\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Identifying endogenous regulators addressed how TgCPB activity is controlled; toxostatins inhibit it at nanomolar potency, though overexpression did not alter invasion or growth.\",\n      \"evidence\": \"Cloning and recombinant expression of ICPs/toxostatins, enzyme inhibition assays, and transgenic toxostatin-1 overexpression with phenotypic readouts\",\n      \"pmids\": [\"19111576\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Lack of phenotype leaves physiological role of the inhibitor unclear\", \"Specificity of toxostatins for TgCPB versus other proteases not fully resolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Determining how TgCPB is activated and where it acts revised the field: it requires TgCPL for maturation and resides in the VAC, not the rhoptries, and is dispensable for rhoptry biogenesis.\",\n      \"evidence\": \"In vitro recombinant maturation assay, validated antibody immunolocalization, and TgCPB knock-out analysis of rhoptry morphology and protein processing\",\n      \"pmids\": [\"23250753\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"VAC-resident substrates of TgCPB not defined\", \"How TgCPB contributes to invasion/growth given VAC localization is unresolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Extending TgCPB's relevance to host response, its release into the host cytosol was placed downstream of ROS and upstream of inflammasome-driven pyroptosis in infected placental cells.\",\n      \"evidence\": \"Cathepsin B inhibitor and ROS scavenger treatment, inflammasome-specific siRNA, and assays of caspase-1 cleavage, IL-1\\u03b2 maturation, and gasdermin D cleavage in infected trophoblast/amniotic cells\",\n      \"pmids\": [\"37741453\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of TgCPB release into host cytosol not defined\", \"Direct molecular link between TgCPB and each inflammasome sensor not established\", \"Pharmacological/siRNA readouts only, single cell context\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The physiological substrates of TgCPB within the VAC and the molecular basis by which it promotes invasion and intracellular growth remain undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No endogenous VAC substrate identified\", \"Causal mechanism linking VAC localization to invasion phenotype unresolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0004197\", \"supporting_discovery_ids\": [0, 2], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0004175\", \"supporting_discovery_ids\": [2], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [4], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0007566\", \"supporting_discovery_ids\": [0, 1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0070269\", \"supporting_discovery_ids\": [5], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0002221\", \"supporting_discovery_ids\": [5], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"TgCPL (cathepsin L; matures TgCPB zymogen) [#4]\",\n      \"Toxostatins/ICPs (endogenous nanomolar cysteine proteinase inhibitors) [#3]\"\n    ],\n    \"other_free_text\": [\n      \"TgCPB is a single-copy gene (tgcp1) encoding an active refoldable cysteine protease [#0].\",\n      \"TgCPB cannot self-mature and depends on TgCPL for zymogen activation [#4].\",\n      \"TgCPB knock-out parasites have normal rhoptry morphology and rhoptry protein maturation, so TgCPB is dispensable for rhoptry biogenesis [#4].\",\n      \"TgCPB mRNA is undetectable in in vivo bradyzoites, indicating stage-specific expression [#2].\",\n      \"In infected host placental cells, TgCPB acts downstream of ROS and upstream of NLRP1/NLRP3/NLRC4/AIM2 inflammasome activation and pyroptosis [#5].\"\n    ]\n  },\n  \"strain_conflicts\": []\n}","audit_flag":null,"strains":[{"strain":"ME49","gene_id":"TGME49_249670","name":null,"product":"cathepsin B","uniprot_acc":"A0A125YP92","chromosome":"TGME49_chrXII","start_pos":4720754},{"strain":"GT1","gene_id":"TGGT1_249670","name":null,"product":"cathepsin B","uniprot_acc":null,"chromosome":"TGGT1_chrXII","start_pos":4657429},{"strain":"RH88","gene_id":"TGRH88_063410","name":null,"product":"cathepsin B","uniprot_acc":null,"chromosome":"CM023093","start_pos":4779336},{"strain":"VEG","gene_id":"TGVEG_249670","name":null,"product":"cathepsin B","uniprot_acc":"B6KHH7","chromosome":"TGVEG_chrXII","start_pos":4696600}]}