{"gene":"TG_264050","gene_symbol":"FTS","run_date":"2026-09-08T14:08:29","timeline":{"discoveries":[{"year":2023,"finding":"TgFTS (Fused Toes homolog) forms a complex with TgHOOK and a coccidian-specific partner HIP (HOOK interacting partner), constituting a partially conserved FHF-like complex in T. gondii that regulates apical microneme positioning and exocytosis.","method":"Co-immunoprecipitation / complex characterization; conditional depletion with phenotypic readout (microneme secretion, motility, invasion, egress assays)","journal":"mBio","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal complex identification plus conditional depletion with multiple orthogonal phenotypic readouts, replicated independently in two labs (PMID:37093045 and PMID:37933960)","pmids":["37093045","37933960"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"finding":"Conditional depletion of TgFTS impairs apical positioning and secretion of micronemes, leading to defects in egress, motility, host cell attachment, and invasion, demonstrating an essential role for FTS in apical exocytosis of secretory organelles.","method":"Conditional depletion (auxin-inducible degron or similar), microneme secretion assay, invasion/egress/motility assays","journal":"mBio","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional loss-of-function with multiple orthogonal functional readouts, replicated across two independent studies","pmids":["37093045","37933960"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"finding":"TgHOOK and TgFTS colocalize at the parasite apical tip, consistent with their role in apical vesicular trafficking of micronemes, and FTS is required for rapid apical trafficking of micronemes as parasites initiate motility.","method":"Fluorescence microscopy (co-localization); live imaging of microneme trafficking upon conditional depletion","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization experiment tied to functional consequence via conditional KO, single lab for trafficking observation","pmids":["37933960"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"finding":"FTS is a substrate-complex partner of the CDPK1 signaling pathway: HOOK (an FTS complex member) is phosphorylated in a CDPK1-dependent manner, placing the FTS-HOOK complex downstream of Ca2+-regulated kinase signaling in microneme exocytosis.","method":"Sub-minute resolution phosphoproteomics; bio-orthogonal labeling of CDPK1 kinase substrates","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — phosphoproteomic identification is rigorous (chemical-genetic kinase substrate labeling), but pathway placement of FTS specifically is inferred from HOOK being the direct substrate rather than FTS itself being directly phosphorylated","pmids":["37933960"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"current_model":"TgFTS forms a partially conserved FHF-like trafficking adaptor complex with TgHOOK and the coccidian-specific protein HIP at the parasite apical tip; this complex acts downstream of CDPK1-dependent Ca2+ signaling to mediate apical vesicular trafficking and exocytosis of micronemes, and its loss blocks microneme secretion, rendering parasites unable to attach to, invade, and egress from host cells."},"narrative":{"mechanistic_narrative":"TgFTS (Fused Toes homolog) is a component of a partially conserved FHF-like trafficking adaptor complex in Toxoplasma gondii, assembling with TgHOOK and the coccidian-specific protein HIP (HOOK interacting partner) to control apical positioning and regulated exocytosis of micronemes [PMID:37093045, PMID:37933960]. FTS and HOOK colocalize at the parasite apical tip, where FTS is required for rapid apical trafficking of micronemes as parasites initiate motility [PMID:37933960]. Conditional depletion of FTS impairs microneme secretion and consequently blocks host cell attachment, motility, invasion, and egress, establishing this complex as essential for the secretory organelle exocytosis that underlies the lytic cycle [PMID:37093045, PMID:37933960]. The complex operates downstream of Ca2+-regulated kinase signaling: HOOK is phosphorylated in a CDPK1-dependent manner, placing the FTS-HOOK complex under control of CDPK1 during microneme exocytosis [PMID:37933960].","teleology":[{"year":2023,"claim":"It was unknown how micronemes are positioned and trafficked to the apical tip for regulated secretion; identifying FTS as part of an FHF-like complex with HOOK and HIP established a conserved adaptor machinery governing apical microneme exocytosis.","evidence":"Co-immunoprecipitation and complex characterization with conditional depletion and microneme secretion/motility/invasion/egress readouts in T. gondii","pmids":["37093045","37933960"],"confidence":"High","gaps":["Molecular architecture of the FTS-HOOK-HIP complex is not resolved structurally","The direct cargo-adaptor or motor linkage mediating trafficking is not defined"],"attribution":[]},{"year":2023,"claim":"Whether FTS was functionally required rather than merely a complex member was open; conditional loss-of-function showed FTS is essential for apical microneme positioning and secretion, and thus for the attach-invade-egress lytic cycle.","evidence":"Conditional depletion with microneme secretion, invasion, egress, and motility assays in T. gondii","pmids":["37093045","37933960"],"confidence":"High","gaps":["Whether FTS loss affects other secretory organelles (e.g. rhoptries, dense granules) is not addressed","The specific step in exocytosis blocked by FTS loss is not pinpointed"],"attribution":[]},{"year":2023,"claim":"The subcellular site and dynamic role of FTS were unclear; imaging placed FTS and HOOK at the apical tip and demonstrated FTS is required for rapid apical microneme trafficking during motility initiation.","evidence":"Fluorescence co-localization and live imaging of microneme trafficking upon conditional depletion in T. gondii","pmids":["37933960"],"confidence":"Medium","gaps":["Single-lab observation for the trafficking dynamics","The cytoskeletal or motor track along which trafficking occurs is not identified"],"attribution":[]},{"year":2023,"claim":"How the FTS complex is coupled to secretory signaling was unknown; CDPK1-dependent phosphorylation of HOOK placed the FTS-HOOK complex downstream of Ca2+-regulated kinase signaling in microneme exocytosis.","evidence":"Sub-minute phosphoproteomics with bio-orthogonal CDPK1 substrate labeling in T. gondii","pmids":["37933960"],"confidence":"Medium","gaps":["FTS itself was not shown to be directly phosphorylated; pathway placement of FTS is inferred via HOOK","The functional consequence of HOOK phosphorylation on complex activity is not established"],"attribution":[]},{"year":null,"claim":"The structural organization of the FTS-HOOK-HIP complex and the direct molecular link between this adaptor and the trafficking/exocytic machinery remain undefined.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of the complex","No identified motor or cargo receptor bridging FTS to microneme transport","Role of FTS outside microneme trafficking unexplored"],"attribution":[]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["FHF-like complex (TgFTS-TgHOOK-HIP)"],"partners":["TGHOOK","HIP (HOOK INTERACTING PARTNER)","CDPK1 (UPSTREAM KINASE ACTING VIA HOOK PHOSPHORYLATION)"],"other_free_text":["TgFTS is required for apical positioning and rapid trafficking of micronemes and their regulated exocytosis, essential for host-cell attachment, invasion, motility, and egress.","FTS-HOOK complex acts downstream of Ca2+/CDPK1 signaling; HOOK, not FTS itself, is the demonstrated direct CDPK1 substrate."]},"strain_conflicts":[]},"prefetch_data":{},"corpus_meta":[{"pmid":"37933960","id":"PMC_37933960","title":"Analysis of CDPK1 targets identifies a trafficking adaptor complex that regulates microneme exocytosis in Toxoplasma.","date":"2023","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/37933960","citation_count":13,"is_preprint":false},{"pmid":"37093045","id":"PMC_37093045","title":"Toxoplasma gondii HOOK-FTS-HIP Complex is Critical for Secretory Organelle Discharge during Motility, Invasion, and Egress.","date":"2023","source":"mBio","url":"https://pubmed.ncbi.nlm.nih.gov/37093045","citation_count":6,"is_preprint":false},{"pmid":"36712004","id":"PMC_36712004","title":"Analysis of CDPK1 targets identifies a trafficking adaptor complex that regulates microneme exocytosis in Toxoplasma.","date":"2023","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/36712004","citation_count":4,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":4119,"output_tokens":1117,"usd":0.014556,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":6027,"output_tokens":2106,"usd":0.041392,"stage2_stop_reason":"end_turn"},"total_usd":0.055948,"stage1_batch_id":"msgbatch_015xmQKDRqnTh9anE4m7LiD6","stage2_batch_id":"msgbatch_01JLpkFTVhoQBNgqHCKFrVVU","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2023,\n      \"finding\": \"TgFTS (Fused Toes homolog) forms a complex with TgHOOK and a coccidian-specific partner HIP (HOOK interacting partner), constituting a partially conserved FHF-like complex in T. gondii that regulates apical microneme positioning and exocytosis.\",\n      \"method\": \"Co-immunoprecipitation / complex characterization; conditional depletion with phenotypic readout (microneme secretion, motility, invasion, egress assays)\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal complex identification plus conditional depletion with multiple orthogonal phenotypic readouts, replicated independently in two labs (PMID:37093045 and PMID:37933960)\",\n      \"pmids\": [\"37093045\", \"37933960\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Conditional depletion of TgFTS impairs apical positioning and secretion of micronemes, leading to defects in egress, motility, host cell attachment, and invasion, demonstrating an essential role for FTS in apical exocytosis of secretory organelles.\",\n      \"method\": \"Conditional depletion (auxin-inducible degron or similar), microneme secretion assay, invasion/egress/motility assays\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional loss-of-function with multiple orthogonal functional readouts, replicated across two independent studies\",\n      \"pmids\": [\"37093045\", \"37933960\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TgHOOK and TgFTS colocalize at the parasite apical tip, consistent with their role in apical vesicular trafficking of micronemes, and FTS is required for rapid apical trafficking of micronemes as parasites initiate motility.\",\n      \"method\": \"Fluorescence microscopy (co-localization); live imaging of microneme trafficking upon conditional depletion\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization experiment tied to functional consequence via conditional KO, single lab for trafficking observation\",\n      \"pmids\": [\"37933960\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"FTS is a substrate-complex partner of the CDPK1 signaling pathway: HOOK (an FTS complex member) is phosphorylated in a CDPK1-dependent manner, placing the FTS-HOOK complex downstream of Ca2+-regulated kinase signaling in microneme exocytosis.\",\n      \"method\": \"Sub-minute resolution phosphoproteomics; bio-orthogonal labeling of CDPK1 kinase substrates\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — phosphoproteomic identification is rigorous (chemical-genetic kinase substrate labeling), but pathway placement of FTS specifically is inferred from HOOK being the direct substrate rather than FTS itself being directly phosphorylated\",\n      \"pmids\": [\"37933960\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    }\n  ],\n  \"current_model\": \"TgFTS forms a partially conserved FHF-like trafficking adaptor complex with TgHOOK and the coccidian-specific protein HIP at the parasite apical tip; this complex acts downstream of CDPK1-dependent Ca2+ signaling to mediate apical vesicular trafficking and exocytosis of micronemes, and its loss blocks microneme secretion, rendering parasites unable to attach to, invade, and egress from host cells.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"TgFTS (Fused Toes homolog) is a component of a partially conserved FHF-like trafficking adaptor complex in Toxoplasma gondii, assembling with TgHOOK and the coccidian-specific protein HIP (HOOK interacting partner) to control apical positioning and regulated exocytosis of micronemes [#0]. FTS and HOOK colocalize at the parasite apical tip, where FTS is required for rapid apical trafficking of micronemes as parasites initiate motility [#2]. Conditional depletion of FTS impairs microneme secretion and consequently blocks host cell attachment, motility, invasion, and egress, establishing this complex as essential for the secretory organelle exocytosis that underlies the lytic cycle [#1]. The complex operates downstream of Ca2+-regulated kinase signaling: HOOK is phosphorylated in a CDPK1-dependent manner, placing the FTS-HOOK complex under control of CDPK1 during microneme exocytosis [#3].\",\n  \"teleology\": [\n    {\n      \"year\": 2023,\n      \"claim\": \"It was unknown how micronemes are positioned and trafficked to the apical tip for regulated secretion; identifying FTS as part of an FHF-like complex with HOOK and HIP established a conserved adaptor machinery governing apical microneme exocytosis.\",\n      \"evidence\": \"Co-immunoprecipitation and complex characterization with conditional depletion and microneme secretion/motility/invasion/egress readouts in T. gondii\",\n      \"pmids\": [\"37093045\", \"37933960\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular architecture of the FTS-HOOK-HIP complex is not resolved structurally\", \"The direct cargo-adaptor or motor linkage mediating trafficking is not defined\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Whether FTS was functionally required rather than merely a complex member was open; conditional loss-of-function showed FTS is essential for apical microneme positioning and secretion, and thus for the attach-invade-egress lytic cycle.\",\n      \"evidence\": \"Conditional depletion with microneme secretion, invasion, egress, and motility assays in T. gondii\",\n      \"pmids\": [\"37093045\", \"37933960\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether FTS loss affects other secretory organelles (e.g. rhoptries, dense granules) is not addressed\", \"The specific step in exocytosis blocked by FTS loss is not pinpointed\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"The subcellular site and dynamic role of FTS were unclear; imaging placed FTS and HOOK at the apical tip and demonstrated FTS is required for rapid apical microneme trafficking during motility initiation.\",\n      \"evidence\": \"Fluorescence co-localization and live imaging of microneme trafficking upon conditional depletion in T. gondii\",\n      \"pmids\": [\"37933960\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab observation for the trafficking dynamics\", \"The cytoskeletal or motor track along which trafficking occurs is not identified\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"How the FTS complex is coupled to secretory signaling was unknown; CDPK1-dependent phosphorylation of HOOK placed the FTS-HOOK complex downstream of Ca2+-regulated kinase signaling in microneme exocytosis.\",\n      \"evidence\": \"Sub-minute phosphoproteomics with bio-orthogonal CDPK1 substrate labeling in T. gondii\",\n      \"pmids\": [\"37933960\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"FTS itself was not shown to be directly phosphorylated; pathway placement of FTS is inferred via HOOK\", \"The functional consequence of HOOK phosphorylation on complex activity is not established\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The structural organization of the FTS-HOOK-HIP complex and the direct molecular link between this adaptor and the trafficking/exocytic machinery remain undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of the complex\", \"No identified motor or cargo receptor bridging FTS to microneme transport\", \"Role of FTS outside microneme trafficking unexplored\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0030674\", \"supporting_discovery_ids\": [0, 2], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0020009\", \"supporting_discovery_ids\": [2], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0017157\", \"supporting_discovery_ids\": [0, 1, 3], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0006887\", \"supporting_discovery_ids\": [1, 2], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"complexes\": [\"FHF-like complex (TgFTS-TgHOOK-HIP)\"],\n    \"partners\": [\"TgHOOK\", \"HIP (HOOK interacting partner)\", \"CDPK1 (upstream kinase acting via HOOK phosphorylation)\"],\n    \"other_free_text\": [\n      \"TgFTS is required for apical positioning and rapid trafficking of micronemes and their regulated exocytosis, essential for host-cell attachment, invasion, motility, and egress.\",\n      \"FTS-HOOK complex acts downstream of Ca2+/CDPK1 signaling; HOOK, not FTS itself, is the demonstrated direct CDPK1 substrate.\"\n    ]\n  },\n  \"strain_conflicts\": []\n}\n```","audit_flag":null,"strains":[{"strain":"ME49","gene_id":"TGME49_264050","name":"FTS","product":"fused toes protein homolog FTS","uniprot_acc":"S8GMP5","chromosome":"TGME49_chrVIIb","start_pos":216161},{"strain":"GT1","gene_id":"TGGT1_264050","name":null,"product":"ubiquitin-conjugating enzyme subfamily protein","uniprot_acc":null,"chromosome":"TGGT1_chrVIIb","start_pos":189077},{"strain":"RH88","gene_id":"TGRH88_067070","name":null,"product":"ubiquitin-conjugating enzyme subfamily protein","uniprot_acc":null,"chromosome":"CM023089","start_pos":227270},{"strain":"VEG","gene_id":"TGVEG_264050","name":null,"product":"ubiquitin-conjugating enzyme subfamily protein","uniprot_acc":"B9Q0X8","chromosome":"TGVEG_chrVIIb","start_pos":220302}]}