{"gene":"TG_218760","gene_symbol":"alphaSNAP","run_date":"2026-09-08T11:06:34","timeline":{"discoveries":[{"year":1999,"finding":"Recombinant bovine alpha-SNAP augments constitutive, calcium-independent dense granule secretion in streptolysin O-permeabilized Toxoplasma gondii parasites, demonstrating that the NSF/SNAP/SNARE/Rab machinery participates in dense granule release and that mammalian alpha-SNAP can functionally substitute for the parasite homologue.","method":"Streptolysin O-permeabilized parasite secretion assay with recombinant bovine alpha-SNAP; N-ethylmaleimide inhibition; recombinant Rab-GDI inhibition; GTPγS stimulation","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional reconstitution in permeabilized parasite system with multiple pharmacological tools and recombinant proteins, single lab but several orthogonal manipulations","pmids":["9891012"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2015,"finding":"Toxoplasma gondii αSNAP is phosphorylated, and this phosphorylation is required for its correct function in controlling secretory traffic; conditional expression of a non-phosphorylatable form of αSNAP causes Golgi fragmentation and vesiculation of all downstream secretory organelles (including micronemes, rhoptries, and dense granules), and also disrupts apicoplast biogenesis, revealing phosphorylation as a regulatory mechanism for cis-SNARE complex disassembly and vesicle fusion during the secretory pathway.","method":"Conditional (inducible) expression of non-phosphorylatable αSNAP mutant; fluorescence microscopy of organelle markers; assessment of Golgi, secretory organelle, and apicoplast morphology during intracellular development","journal":"Traffic (Copenhagen, Denmark)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional genetic approach with defined organelle phenotypes and post-translational modification validation, single lab with multiple orthogonal organelle readouts","pmids":["26566590"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"current_model":"Toxoplasma gondii αSNAP is a component of the NSF/SNAP/SNARE/Rab vesicle fusion machinery that drives constitutive, calcium-independent dense granule secretion and controls cis-SNARE complex disassembly throughout the secretory pathway; its phosphorylation is additionally required for correct secretory organelle biogenesis, as a non-phosphorylatable form causes Golgi fragmentation, vesiculation of downstream secretory organelles, and disruption of apicoplast integrity."},"narrative":{"mechanistic_narrative":"Toxoplasma gondii αSNAP is a component of the NSF/SNAP/SNARE/Rab vesicle-fusion machinery that drives dense granule secretion in the parasite [PMID:9891012]. Reconstitution in streptolysin O-permeabilized parasites showed that recombinant αSNAP augments constitutive, calcium-independent dense granule release, that this release is N-ethylmaleimide-sensitive and Rab-GDI-inhibitable, and that mammalian αSNAP functionally substitutes for the parasite protein [PMID:9891012]. αSNAP is phosphorylated, and this modification is required for its role in cis-SNARE complex disassembly and secretory traffic: conditional expression of a non-phosphorylatable form causes Golgi fragmentation, vesiculation of downstream secretory organelles (micronemes, rhoptries, dense granules), and disruption of apicoplast biogenesis [PMID:26566590]. Beyond these findings, no further mechanistic detail has been characterized in the available corpus.","teleology":[{"year":1999,"claim":"Whether the NSF/SNAP/SNARE/Rab fusion machinery participates in parasite dense granule secretion was unknown; adding recombinant αSNAP established that αSNAP-dependent membrane fusion drives constitutive, calcium-independent dense granule release.","evidence":"Streptolysin O-permeabilized T. gondii secretion assay with recombinant bovine alpha-SNAP, N-ethylmaleimide inhibition, Rab-GDI inhibition, and GTPγS stimulation","pmids":["9891012"],"confidence":"Medium","gaps":["Endogenous parasite αSNAP not directly assayed — activity inferred from mammalian ortholog substitution","Direct SNARE and NSF partners in the parasite not identified","Does not address the enzyme's role beyond dense granules"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2015,"claim":"How αSNAP function is regulated and whether it acts across the whole secretory pathway was unknown; a non-phosphorylatable mutant revealed that αSNAP phosphorylation controls cis-SNARE disassembly and is required for secretory organelle and apicoplast biogenesis.","evidence":"Conditional expression of a non-phosphorylatable αSNAP mutant with fluorescence microscopy of Golgi, secretory organelle, and apicoplast markers during intracellular development","pmids":["26566590"],"confidence":"Medium","gaps":["The kinase responsible for αSNAP phosphorylation is not identified","The phosphorylated residue(s) and how phosphorylation alters SNARE disassembly biochemically are not defined","Whether apicoplast disruption is a direct or downstream consequence is unresolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":null,"claim":"The kinase, phosphosites, and direct SNARE/NSF partners of parasite αSNAP remain uncharacterized in the available corpus.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No kinase assigned to αSNAP phosphorylation","No structural or biochemical model of αSNAP-mediated cis-SNARE disassembly in the parasite","Direct parasite SNARE/NSF binding partners not mapped"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["NSF/SNAP/SNARE/Rab vesicle fusion machinery"],"partners":["NSF","SNARE PROTEINS","RAB GTPASES (RAB-GDI-SENSITIVE)"],"other_free_text":["Drives constitutive, calcium-independent dense granule secretion [#0]","Phosphorylation required for cis-SNARE complex disassembly and secretory organelle biogenesis [#1]","Non-phosphorylatable form causes Golgi fragmentation, vesiculation of micronemes/rhoptries/dense granules, and apicoplast disruption [#1]","Mammalian alpha-SNAP functionally substitutes for the parasite protein in permeabilized secretion assays [#0]"]},"strain_conflicts":[]},"prefetch_data":{},"corpus_meta":[{"pmid":"9891012","id":"PMC_9891012","title":"Constitutive calcium-independent release of Toxoplasma gondii dense granules occurs through the NSF/SNAP/SNARE/Rab machinery.","date":"1999","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9891012","citation_count":50,"is_preprint":false},{"pmid":"26566590","id":"PMC_26566590","title":"Phosphorylation of αSNAP is Required for Secretory Organelle Biogenesis in Toxoplasma gondii.","date":"2015","source":"Traffic (Copenhagen, Denmark)","url":"https://pubmed.ncbi.nlm.nih.gov/26566590","citation_count":8,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":3301,"output_tokens":782,"usd":0.010816,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":5591,"output_tokens":1979,"usd":0.038715,"stage2_stop_reason":"end_turn"},"total_usd":0.049531,"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\": 1999,\n      \"finding\": \"Recombinant bovine alpha-SNAP augments constitutive, calcium-independent dense granule secretion in streptolysin O-permeabilized Toxoplasma gondii parasites, demonstrating that the NSF/SNAP/SNARE/Rab machinery participates in dense granule release and that mammalian alpha-SNAP can functionally substitute for the parasite homologue.\",\n      \"method\": \"Streptolysin O-permeabilized parasite secretion assay with recombinant bovine alpha-SNAP; N-ethylmaleimide inhibition; recombinant Rab-GDI inhibition; GTPγS stimulation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional reconstitution in permeabilized parasite system with multiple pharmacological tools and recombinant proteins, single lab but several orthogonal manipulations\",\n      \"pmids\": [\"9891012\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Toxoplasma gondii αSNAP is phosphorylated, and this phosphorylation is required for its correct function in controlling secretory traffic; conditional expression of a non-phosphorylatable form of αSNAP causes Golgi fragmentation and vesiculation of all downstream secretory organelles (including micronemes, rhoptries, and dense granules), and also disrupts apicoplast biogenesis, revealing phosphorylation as a regulatory mechanism for cis-SNARE complex disassembly and vesicle fusion during the secretory pathway.\",\n      \"method\": \"Conditional (inducible) expression of non-phosphorylatable αSNAP mutant; fluorescence microscopy of organelle markers; assessment of Golgi, secretory organelle, and apicoplast morphology during intracellular development\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional genetic approach with defined organelle phenotypes and post-translational modification validation, single lab with multiple orthogonal organelle readouts\",\n      \"pmids\": [\"26566590\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    }\n  ],\n  \"current_model\": \"Toxoplasma gondii αSNAP is a component of the NSF/SNAP/SNARE/Rab vesicle fusion machinery that drives constitutive, calcium-independent dense granule secretion and controls cis-SNARE complex disassembly throughout the secretory pathway; its phosphorylation is additionally required for correct secretory organelle biogenesis, as a non-phosphorylatable form causes Golgi fragmentation, vesiculation of downstream secretory organelles, and disruption of apicoplast integrity.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"Toxoplasma gondii \\u03b1SNAP is a component of the NSF/SNAP/SNARE/Rab vesicle-fusion machinery that drives dense granule secretion in the parasite [#0]. Reconstitution in streptolysin O-permeabilized parasites showed that recombinant \\u03b1SNAP augments constitutive, calcium-independent dense granule release, that this release is N-ethylmaleimide-sensitive and Rab-GDI-inhibitable, and that mammalian \\u03b1SNAP functionally substitutes for the parasite protein [#0]. \\u03b1SNAP is phosphorylated, and this modification is required for its role in cis-SNARE complex disassembly and secretory traffic: conditional expression of a non-phosphorylatable form causes Golgi fragmentation, vesiculation of downstream secretory organelles (micronemes, rhoptries, dense granules), and disruption of apicoplast biogenesis [#1]. Beyond these findings, no further mechanistic detail has been characterized in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Whether the NSF/SNAP/SNARE/Rab fusion machinery participates in parasite dense granule secretion was unknown; adding recombinant \\u03b1SNAP established that \\u03b1SNAP-dependent membrane fusion drives constitutive, calcium-independent dense granule release.\",\n      \"evidence\": \"Streptolysin O-permeabilized T. gondii secretion assay with recombinant bovine alpha-SNAP, N-ethylmaleimide inhibition, Rab-GDI inhibition, and GTP\\u03b3S stimulation\",\n      \"pmids\": [\"9891012\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Endogenous parasite \\u03b1SNAP not directly assayed \\u2014 activity inferred from mammalian ortholog substitution\",\n        \"Direct SNARE and NSF partners in the parasite not identified\",\n        \"Does not address the enzyme's role beyond dense granules\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"How \\u03b1SNAP function is regulated and whether it acts across the whole secretory pathway was unknown; a non-phosphorylatable mutant revealed that \\u03b1SNAP phosphorylation controls cis-SNARE disassembly and is required for secretory organelle and apicoplast biogenesis.\",\n      \"evidence\": \"Conditional expression of a non-phosphorylatable \\u03b1SNAP mutant with fluorescence microscopy of Golgi, secretory organelle, and apicoplast markers during intracellular development\",\n      \"pmids\": [\"26566590\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"The kinase responsible for \\u03b1SNAP phosphorylation is not identified\",\n        \"The phosphorylated residue(s) and how phosphorylation alters SNARE disassembly biochemically are not defined\",\n        \"Whether apicoplast disruption is a direct or downstream consequence is unresolved\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The kinase, phosphosites, and direct SNARE/NSF partners of parasite \\u03b1SNAP remain uncharacterized in the available corpus.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No kinase assigned to \\u03b1SNAP phosphorylation\",\n        \"No structural or biochemical model of \\u03b1SNAP-mediated cis-SNARE disassembly in the parasite\",\n        \"Direct parasite SNARE/NSF binding partners not mapped\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0019905\", \"supporting_discovery_ids\": [0, 1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0006886\", \"supporting_discovery_ids\": [0, 1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0006906\", \"supporting_discovery_ids\": [1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"complexes\": [\"NSF/SNAP/SNARE/Rab vesicle fusion machinery\"],\n    \"partners\": [\"NSF\", \"SNARE proteins\", \"Rab GTPases (Rab-GDI-sensitive)\"],\n    \"other_free_text\": [\n      \"Drives constitutive, calcium-independent dense granule secretion [#0]\",\n      \"Phosphorylation required for cis-SNARE complex disassembly and secretory organelle biogenesis [#1]\",\n      \"Non-phosphorylatable form causes Golgi fragmentation, vesiculation of micronemes/rhoptries/dense granules, and apicoplast disruption [#1]\",\n      \"Mammalian alpha-SNAP functionally substitutes for the parasite protein in permeabilized secretion assays [#0]\"\n    ]\n  },\n  \"strain_conflicts\": []\n}","audit_flag":null,"strains":[{"strain":"ME49","gene_id":"TGME49_218760","name":"alphaSNAP","product":"alpha-soluble NSF attachment protein","uniprot_acc":"S8EUM1","chromosome":"TGME49_chrXII","start_pos":1323558},{"strain":"GT1","gene_id":"TGGT1_218760","name":null,"product":"putative SNAP protein (soluble N-ethylmaleimide-sensitive factor Attachment Protein)","uniprot_acc":null,"chromosome":"TGGT1_chrXII","start_pos":1264192},{"strain":"RH88","gene_id":"TGRH88_058740","name":null,"product":"putative SNAP protein (soluble N-ethylmaleimide-sensitive factor Attachment Protein)","uniprot_acc":null,"chromosome":"CM023093","start_pos":1335983},{"strain":"VEG","gene_id":"TGVEG_218760","name":null,"product":"putative SNAP protein (soluble N-ethylmaleimide-sensitive factor Attachment Protein)","uniprot_acc":"B9PQH9","chromosome":"TGVEG_chrXII","start_pos":1297326}]}