{"gene":"TG_214090","gene_symbol":"","run_date":"2026-09-08T11:06:26","timeline":{"discoveries":[{"year":2000,"finding":"TgMIC5 is expressed as a preproprotein that is proteolytically processed by signal peptidase to generate a proprotein, which is then further processed to a mature 22 kDa protein stored in micronemes before secretion.","method":"Molecular cloning, DNA sequence analysis, cell fractionation, immunofluorescence, and immunoelectron microscopy","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct biochemical and imaging experiments in a single lab demonstrating signal peptidase cleavage as part of a two-step proteolytic maturation pathway","pmids":["11087916"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2011,"finding":"Signal peptidase cleavage defines the N-terminus of MIC propeptides, and specific aliphatic residues at positions immediately following the signal peptidase cleavage site (e.g., valine at +3 of proM2AP and leucine at +1 of proMIC5) are required for forward targeting of micronemal proteins to the micronemes.","method":"N-terminal deletion and mutational analysis (site-directed mutagenesis), propeptide domain swapping experiments, trafficking assays in T. gondii","journal":"Traffic (Copenhagen, Denmark)","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal domain-swap experiments plus systematic mutagenesis across multiple MICs and an Eimeria ortholog, all confirming the same aliphatic-residue rule post-signal-peptidase cleavage","pmids":["21438967"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"current_model":"In Toxoplasma gondii, signal peptidase cleaves micronemal preproproteins (e.g., TgMIC5, TgM2AP) to generate propeptides whose extreme N-terminal aliphatic residues (leucine or valine immediately after the cleavage site) are essential for forward trafficking of the resulting proproteins to the micronemes, where a second proteolytic event produces the mature secreted proteins."},"narrative":{"mechanistic_narrative":"In Toxoplasma gondii, signal peptidase initiates a two-step proteolytic maturation pathway for micronemal preproproteins, cleaving the signal peptide to convert preproproteins such as TgMIC5 into proproteins that are subsequently processed to their mature secreted forms stored in the micronemes [PMID:11087916]. The signal peptidase cleavage event defines the N-terminus of the MIC propeptides, and the aliphatic residues exposed immediately after the cleavage site—valine at +3 of proM2AP and leucine at +1 of proMIC5—are required for forward trafficking of these proteins to the micronemes [PMID:21438967]. Beyond its role in generating trafficking-competent propeptide N-termini, no further mechanistic detail of the signal peptidase itself has been characterized in the available corpus.","teleology":[{"year":2000,"claim":"Established that a micronemal protein is not synthesized in mature form but passes through a signal-peptidase-dependent maturation cascade, defining the proteolytic logic of microneme protein biogenesis.","evidence":"Molecular cloning, cell fractionation, immunofluorescence, and immunoelectron microscopy of TgMIC5 in T. gondii","pmids":["11087916"],"confidence":"Medium","gaps":["Does not identify the signal peptidase enzyme itself or its catalytic subunits","The identity of the protease performing the second maturation step is not established","Functional consequence of blocking signal peptidase cleavage is not tested"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2011,"claim":"Resolved why signal peptidase cleavage matters beyond signal-peptide removal by showing that the aliphatic residue it exposes at the propeptide N-terminus is the trafficking determinant directing proproteins to the micronemes.","evidence":"N-terminal deletion, site-directed mutagenesis, and propeptide domain-swapping trafficking assays across multiple MICs and an Eimeria ortholog in T. gondii","pmids":["21438967"],"confidence":"High","gaps":["The receptor or machinery that reads the aliphatic N-terminal residue is not identified","How the exposed residue is recognized during forward trafficking is unresolved","The signal peptidase enzyme is inferred as the cleaving activity but not directly characterized"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":null,"claim":"The molecular identity, subunit composition, and catalytic mechanism of the Toxoplasma signal peptidase itself remain uncharacterized in this corpus.","evidence":"","pmids":[],"confidence":"Low","gaps":["No direct biochemical isolation or structural characterization of the signal peptidase enzyme","No identification of the downstream protease mediating the second maturation cleavage","No identification of the trafficking receptor recognizing the aliphatic N-terminal residue"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":[],"partners":["TGMIC5 (PREPROPROTEIN SUBSTRATE)","TGM2AP (PROM2AP SUBSTRATE)"],"other_free_text":["Cleaves micronemal preproproteins to generate proproteins in a two-step maturation pathway [#0].","Cleavage exposes aliphatic N-terminal residues (Leu at +1 of proMIC5, Val at +3 of proM2AP) required for forward trafficking to the micronemes [#1].","The aliphatic-residue trafficking rule was confirmed across multiple MICs and an Eimeria ortholog [#1]."]},"strain_conflicts":[]},"prefetch_data":{},"corpus_meta":[{"pmid":"11087916","id":"PMC_11087916","title":"Molecular characterization of TgMIC5, a proteolytically processed antigen secreted from the micronemes of Toxoplasma gondii.","date":"2000","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/11087916","citation_count":59,"is_preprint":false},{"pmid":"21438967","id":"PMC_21438967","title":"Forward targeting of Toxoplasma gondii proproteins to the micronemes involves conserved aliphatic amino acids.","date":"2011","source":"Traffic (Copenhagen, Denmark)","url":"https://pubmed.ncbi.nlm.nih.gov/21438967","citation_count":29,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":3443,"output_tokens":645,"usd":0.010002,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":5369,"output_tokens":1642,"usd":0.033947,"stage2_stop_reason":"end_turn"},"total_usd":0.043949,"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\": 2000,\n      \"finding\": \"TgMIC5 is expressed as a preproprotein that is proteolytically processed by signal peptidase to generate a proprotein, which is then further processed to a mature 22 kDa protein stored in micronemes before secretion.\",\n      \"method\": \"Molecular cloning, DNA sequence analysis, cell fractionation, immunofluorescence, and immunoelectron microscopy\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct biochemical and imaging experiments in a single lab demonstrating signal peptidase cleavage as part of a two-step proteolytic maturation pathway\",\n      \"pmids\": [\"11087916\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Signal peptidase cleavage defines the N-terminus of MIC propeptides, and specific aliphatic residues at positions immediately following the signal peptidase cleavage site (e.g., valine at +3 of proM2AP and leucine at +1 of proMIC5) are required for forward targeting of micronemal proteins to the micronemes.\",\n      \"method\": \"N-terminal deletion and mutational analysis (site-directed mutagenesis), propeptide domain swapping experiments, trafficking assays in T. gondii\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal domain-swap experiments plus systematic mutagenesis across multiple MICs and an Eimeria ortholog, all confirming the same aliphatic-residue rule post-signal-peptidase cleavage\",\n      \"pmids\": [\"21438967\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    }\n  ],\n  \"current_model\": \"In Toxoplasma gondii, signal peptidase cleaves micronemal preproproteins (e.g., TgMIC5, TgM2AP) to generate propeptides whose extreme N-terminal aliphatic residues (leucine or valine immediately after the cleavage site) are essential for forward trafficking of the resulting proproteins to the micronemes, where a second proteolytic event produces the mature secreted proteins.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"In Toxoplasma gondii, signal peptidase initiates a two-step proteolytic maturation pathway for micronemal preproproteins, cleaving the signal peptide to convert preproproteins such as TgMIC5 into proproteins that are subsequently processed to their mature secreted forms stored in the micronemes [#0]. The signal peptidase cleavage event defines the N-terminus of the MIC propeptides, and the aliphatic residues exposed immediately after the cleavage site—valine at +3 of proM2AP and leucine at +1 of proMIC5—are required for forward trafficking of these proteins to the micronemes [#1]. Beyond its role in generating trafficking-competent propeptide N-termini, no further mechanistic detail of the signal peptidase itself has been characterized in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Established that a micronemal protein is not synthesized in mature form but passes through a signal-peptidase-dependent maturation cascade, defining the proteolytic logic of microneme protein biogenesis.\",\n      \"evidence\": \"Molecular cloning, cell fractionation, immunofluorescence, and immunoelectron microscopy of TgMIC5 in T. gondii\",\n      \"pmids\": [\"11087916\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Does not identify the signal peptidase enzyme itself or its catalytic subunits\",\n        \"The identity of the protease performing the second maturation step is not established\",\n        \"Functional consequence of blocking signal peptidase cleavage is not tested\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Resolved why signal peptidase cleavage matters beyond signal-peptide removal by showing that the aliphatic residue it exposes at the propeptide N-terminus is the trafficking determinant directing proproteins to the micronemes.\",\n      \"evidence\": \"N-terminal deletion, site-directed mutagenesis, and propeptide domain-swapping trafficking assays across multiple MICs and an Eimeria ortholog in T. gondii\",\n      \"pmids\": [\"21438967\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The receptor or machinery that reads the aliphatic N-terminal residue is not identified\",\n        \"How the exposed residue is recognized during forward trafficking is unresolved\",\n        \"The signal peptidase enzyme is inferred as the cleaving activity but not directly characterized\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The molecular identity, subunit composition, and catalytic mechanism of the Toxoplasma signal peptidase itself remain uncharacterized in this corpus.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No direct biochemical isolation or structural characterization of the signal peptidase enzyme\",\n        \"No identification of the downstream protease mediating the second maturation cleavage\",\n        \"No identification of the trafficking receptor recognizing the aliphatic N-terminal residue\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0004252\", \"supporting_discovery_ids\": [0, 1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"GO:0006465\", \"supporting_discovery_ids\": [0], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0015031\", \"supporting_discovery_ids\": [1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"TgMIC5 (preproprotein substrate)\", \"TgM2AP (proM2AP substrate)\"],\n    \"other_free_text\": [\n      \"Cleaves micronemal preproproteins to generate proproteins in a two-step maturation pathway [#0].\",\n      \"Cleavage exposes aliphatic N-terminal residues (Leu at +1 of proMIC5, Val at +3 of proM2AP) required for forward trafficking to the micronemes [#1].\",\n      \"The aliphatic-residue trafficking rule was confirmed across multiple MICs and an Eimeria ortholog [#1].\"\n    ]\n  },\n  \"strain_conflicts\": []\n}","audit_flag":null,"strains":[{"strain":"ME49","gene_id":"TGME49_214090","name":null,"product":"signal peptidase","uniprot_acc":"S8EZH5","chromosome":"TGME49_chrX","start_pos":6017577},{"strain":"GT1","gene_id":"TGGT1_214090","name":null,"product":"signal peptidase","uniprot_acc":null,"chromosome":"TGGT1_chrX","start_pos":5908335},{"strain":"RH88","gene_id":"TGRH88_040430","name":null,"product":"signal peptidase","uniprot_acc":null,"chromosome":"CM023091","start_pos":1507500},{"strain":"VEG","gene_id":"TGVEG_214090","name":null,"product":"signal peptidase","uniprot_acc":"B9QND8","chromosome":"TGVEG_chrX","start_pos":5943767}]}