{"gene":"TG_306920","gene_symbol":"HIP","run_date":"2026-09-08T15:15:13","timeline":{"discoveries":[{"year":2023,"finding":"TgHOOK, TgFTS, and HIP (HOOK interacting partner, a coccidian-specific protein) form a trimeric complex in Toxoplasma gondii, partially conserving the eukaryotic FHF (HOOK-FTS-FHIP) endosomal trafficking complex but with parasite-specific components replacing FHIP.","method":"Co-immunoprecipitation / complex characterization; conditional depletion; colocalization by fluorescence microscopy","journal":"mBio","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal complex identification confirmed by two independent labs (PMID:37093045 and PMID:37933960) using orthogonal methods (Co-IP, proximity labeling, genetic depletion)","pmids":["37093045","37933960"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"finding":"HIP localizes to an apically enriched vesicular pattern and concentrates at the parasite apical tip, where it colocalizes with TgHOOK and TgFTS.","method":"Fluorescence microscopy / colocalization","journal":"mBio","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct localization experiment replicated across two independent studies but without functional mutagenesis of localization determinants","pmids":["37093045","37933960"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"finding":"Conditional depletion of TgHIP impairs apical positioning and secretion of micronemes and leads to severe defects in egress, motility, host cell attachment, and invasion, demonstrating HIP is required for microneme exocytosis.","method":"Conditional knockdown (auxin-inducible degron or equivalent) with secretion assays, motility assays, invasion assays, and egress assays","journal":"mBio","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean conditional depletion with multiple orthogonal phenotypic readouts (secretion, motility, invasion, egress) in a single rigorous study, consistent with findings in the companion paper","pmids":["37093045"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"finding":"HIP (TGGT1_316650) is identified as a CDPK1-dependent phosphorylation substrate, placing it downstream of Ca2+-regulated kinase signaling that controls microneme trafficking.","method":"Sub-minute resolution phosphoproteomics and bio-orthogonal labeling of CDPK1 substrates","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — phosphoproteomics with bio-orthogonal labeling in a single lab; substrate identified but downstream functional consequences of the specific phosphorylation not individually validated","pmids":["37933960","36712004"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":"RH"}]},{"year":2023,"finding":"The HOOK-FTS-HIP complex (partially conserved FHF complex) is required for rapid apical trafficking of micronemes as parasites initiate motility, linking endosomal trafficking machinery to microneme exocytosis.","method":"Live imaging of microneme trafficking; genetic knockouts/knockdowns of complex components; secretion assays","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — two independent labs using genetic depletion combined with live imaging and functional secretion assays establish the same mechanistic conclusion","pmids":["37933960","37093045"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"current_model":"HIP (TGGT1_316650) is a coccidian-specific component of a partially conserved FHF-like endosomal trafficking complex (HOOK–FTS–HIP) that localizes apically in Toxoplasma gondii, acts downstream of CDPK1 phosphorylation, and is required for the apical positioning and Ca2+-regulated exocytosis of micronemes, thereby enabling parasite motility, host cell invasion, and egress."},"narrative":{"mechanistic_narrative":"HIP (TGGT1_316650) is a coccidian-specific protein that functions in an apical endosomal trafficking pathway controlling microneme exocytosis in Toxoplasma gondii [PMID:37093045, PMID:37933960]. It assembles with TgHOOK and TgFTS into a trimeric complex that partially conserves the eukaryotic FHF (HOOK-FTS-FHIP) endosomal trafficking complex, with HIP serving as the parasite-specific component that replaces FHIP [PMID:37093045, PMID:37933960]. The complex localizes in an apically enriched vesicular pattern concentrating at the parasite apical tip [PMID:37093045, PMID:37933960], and is required for the rapid apical trafficking of micronemes as parasites initiate motility [PMID:37933960, PMID:37093045]. Conditional depletion of HIP impairs apical positioning and secretion of micronemes and produces severe defects in egress, motility, host cell attachment, and invasion [PMID:37093045]. HIP is a CDPK1-dependent phosphorylation substrate, placing it downstream of Ca2+-regulated kinase signaling that governs microneme trafficking [PMID:37933960, PMID:36712004].","teleology":[{"year":2023,"claim":"It was unknown whether Toxoplasma possesses an FHF-like endosomal trafficking complex; identifying a trimeric HOOK-FTS-HIP assembly established that the parasite adapts this conserved machinery with a lineage-specific subunit.","evidence":"Co-immunoprecipitation, proximity labeling, and conditional depletion with colocalization microscopy in T. gondii","pmids":["37093045","37933960"],"confidence":"High","gaps":["No structural model of the HOOK-FTS-HIP complex or the HIP-HOOK interface","Stoichiometry and assembly order of the trimer not resolved","How HIP functionally substitutes for FHIP not defined"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"claim":"The subcellular site of HIP action was undefined; localization to an apically enriched vesicular pattern concentrating at the apical tip, colocalizing with TgHOOK and TgFTS, placed the complex where microneme trafficking occurs.","evidence":"Fluorescence microscopy and colocalization in T. gondii","pmids":["37093045","37933960"],"confidence":"Medium","gaps":["Localization determinants not mapped by mutagenesis","Whether apical targeting depends on complex assembly not tested"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"claim":"The functional requirement for HIP was unknown; conditional depletion showed it is needed for apical microneme positioning and secretion, establishing HIP as essential for exocytosis-dependent motility, attachment, invasion, and egress.","evidence":"Conditional knockdown with secretion, motility, invasion, and egress assays in T. gondii","pmids":["37093045"],"confidence":"High","gaps":["Whether microneme secretion defect is a direct trafficking failure or an indirect positioning consequence not separated","Contribution of individual complex subunits to each phenotype not dissected"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"claim":"It was unclear how the trafficking complex is regulated; live imaging linked HOOK-FTS-HIP to rapid apical microneme trafficking at motility onset, connecting endosomal machinery to regulated exocytosis.","evidence":"Live imaging of microneme trafficking with genetic depletion and secretion assays in T. gondii","pmids":["37933960","37093045"],"confidence":"High","gaps":["The motor or adaptor driving microneme movement along the pathway not identified","Kinetic coupling between trafficking and Ca2+ signaling not resolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"claim":"How HIP is integrated with Ca2+ signaling was unknown; identification of HIP as a CDPK1-dependent phosphosubstrate placed it downstream of the kinase controlling microneme discharge.","evidence":"Sub-minute phosphoproteomics and bio-orthogonal labeling of CDPK1 substrates in T. gondii strain RH","pmids":["37933960","36712004"],"confidence":"Medium","gaps":["Functional consequence of the specific phosphorylation site not validated by mutagenesis","Whether phosphorylation regulates complex assembly, localization, or activity unknown"],"attribution":[{"species":"Toxoplasma gondii","strain":"RH"}]},{"year":null,"claim":"How CDPK1 phosphorylation of HIP mechanistically controls microneme trafficking and exocytosis, and the structural basis of the HOOK-FTS-HIP complex, remain open.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No phosphomutant analysis linking specific sites to trafficking function","No structural characterization of the complex","Motor/cargo adaptor connecting the complex to micronemes not identified"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["HOOK-FTS-HIP trimeric complex (parasite FHF-like endosomal trafficking complex)"],"partners":["TGHOOK","TGFTS","CDPK1 (KINASE ACTING UPSTREAM OF HIP)"],"other_free_text":["HIP is a coccidian-specific protein that replaces the FHIP subunit of the conserved eukaryotic FHF complex [#0].","HIP depletion impairs apical microneme positioning, secretion, motility, attachment, invasion, and egress [#2]."]},"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":1300,"usd":0.015929,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":6298,"output_tokens":2606,"usd":0.04832,"stage2_stop_reason":"end_turn"},"total_usd":0.064249,"stage1_batch_id":"msgbatch_01S6GjoYQm8LTPUsdhASdqag","stage2_batch_id":"msgbatch_01VX63RTMdBJqsG6gQMqoCjz","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2023,\n      \"finding\": \"TgHOOK, TgFTS, and HIP (HOOK interacting partner, a coccidian-specific protein) form a trimeric complex in Toxoplasma gondii, partially conserving the eukaryotic FHF (HOOK-FTS-FHIP) endosomal trafficking complex but with parasite-specific components replacing FHIP.\",\n      \"method\": \"Co-immunoprecipitation / complex characterization; conditional depletion; colocalization by fluorescence microscopy\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal complex identification confirmed by two independent labs (PMID:37093045 and PMID:37933960) using orthogonal methods (Co-IP, proximity labeling, genetic depletion)\",\n      \"pmids\": [\"37093045\", \"37933960\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"HIP localizes to an apically enriched vesicular pattern and concentrates at the parasite apical tip, where it colocalizes with TgHOOK and TgFTS.\",\n      \"method\": \"Fluorescence microscopy / colocalization\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct localization experiment replicated across two independent studies but without functional mutagenesis of localization determinants\",\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 TgHIP impairs apical positioning and secretion of micronemes and leads to severe defects in egress, motility, host cell attachment, and invasion, demonstrating HIP is required for microneme exocytosis.\",\n      \"method\": \"Conditional knockdown (auxin-inducible degron or equivalent) with secretion assays, motility assays, invasion assays, and egress assays\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean conditional depletion with multiple orthogonal phenotypic readouts (secretion, motility, invasion, egress) in a single rigorous study, consistent with findings in the companion paper\",\n      \"pmids\": [\"37093045\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"HIP (TGGT1_316650) is identified as a CDPK1-dependent phosphorylation substrate, placing it downstream of Ca2+-regulated kinase signaling that controls microneme trafficking.\",\n      \"method\": \"Sub-minute resolution phosphoproteomics and bio-orthogonal labeling of CDPK1 substrates\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — phosphoproteomics with bio-orthogonal labeling in a single lab; substrate identified but downstream functional consequences of the specific phosphorylation not individually validated\",\n      \"pmids\": [\"37933960\", \"36712004\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"The HOOK-FTS-HIP complex (partially conserved FHF complex) is required for rapid apical trafficking of micronemes as parasites initiate motility, linking endosomal trafficking machinery to microneme exocytosis.\",\n      \"method\": \"Live imaging of microneme trafficking; genetic knockouts/knockdowns of complex components; secretion assays\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — two independent labs using genetic depletion combined with live imaging and functional secretion assays establish the same mechanistic conclusion\",\n      \"pmids\": [\"37933960\", \"37093045\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    }\n  ],\n  \"current_model\": \"HIP (TGGT1_316650) is a coccidian-specific component of a partially conserved FHF-like endosomal trafficking complex (HOOK–FTS–HIP) that localizes apically in Toxoplasma gondii, acts downstream of CDPK1 phosphorylation, and is required for the apical positioning and Ca2+-regulated exocytosis of micronemes, thereby enabling parasite motility, host cell invasion, and egress.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"HIP (TGGT1_316650) is a coccidian-specific protein that functions in an apical endosomal trafficking pathway controlling microneme exocytosis in Toxoplasma gondii [#0, #2]. It assembles with TgHOOK and TgFTS into a trimeric complex that partially conserves the eukaryotic FHF (HOOK-FTS-FHIP) endosomal trafficking complex, with HIP serving as the parasite-specific component that replaces FHIP [#0]. The complex localizes in an apically enriched vesicular pattern concentrating at the parasite apical tip [#1], and is required for the rapid apical trafficking of micronemes as parasites initiate motility [#4]. Conditional depletion of HIP impairs apical positioning and secretion of micronemes and produces severe defects in egress, motility, host cell attachment, and invasion [#2]. HIP is a CDPK1-dependent phosphorylation substrate, placing it downstream of Ca2+-regulated kinase signaling that governs microneme trafficking [#3].\",\n  \"teleology\": [\n    {\n      \"year\": 2023,\n      \"claim\": \"It was unknown whether Toxoplasma possesses an FHF-like endosomal trafficking complex; identifying a trimeric HOOK-FTS-HIP assembly established that the parasite adapts this conserved machinery with a lineage-specific subunit.\",\n      \"evidence\": \"Co-immunoprecipitation, proximity labeling, and conditional depletion with colocalization microscopy in T. gondii\",\n      \"pmids\": [\"37093045\", \"37933960\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No structural model of the HOOK-FTS-HIP complex or the HIP-HOOK interface\",\n        \"Stoichiometry and assembly order of the trimer not resolved\",\n        \"How HIP functionally substitutes for FHIP not defined\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"The subcellular site of HIP action was undefined; localization to an apically enriched vesicular pattern concentrating at the apical tip, colocalizing with TgHOOK and TgFTS, placed the complex where microneme trafficking occurs.\",\n      \"evidence\": \"Fluorescence microscopy and colocalization in T. gondii\",\n      \"pmids\": [\"37093045\", \"37933960\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Localization determinants not mapped by mutagenesis\",\n        \"Whether apical targeting depends on complex assembly not tested\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"The functional requirement for HIP was unknown; conditional depletion showed it is needed for apical microneme positioning and secretion, establishing HIP as essential for exocytosis-dependent motility, attachment, invasion, and egress.\",\n      \"evidence\": \"Conditional knockdown with secretion, motility, invasion, and egress assays in T. gondii\",\n      \"pmids\": [\"37093045\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether microneme secretion defect is a direct trafficking failure or an indirect positioning consequence not separated\",\n        \"Contribution of individual complex subunits to each phenotype not dissected\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"It was unclear how the trafficking complex is regulated; live imaging linked HOOK-FTS-HIP to rapid apical microneme trafficking at motility onset, connecting endosomal machinery to regulated exocytosis.\",\n      \"evidence\": \"Live imaging of microneme trafficking with genetic depletion and secretion assays in T. gondii\",\n      \"pmids\": [\"37933960\", \"37093045\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The motor or adaptor driving microneme movement along the pathway not identified\",\n        \"Kinetic coupling between trafficking and Ca2+ signaling not resolved\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"How HIP is integrated with Ca2+ signaling was unknown; identification of HIP as a CDPK1-dependent phosphosubstrate placed it downstream of the kinase controlling microneme discharge.\",\n      \"evidence\": \"Sub-minute phosphoproteomics and bio-orthogonal labeling of CDPK1 substrates in T. gondii strain RH\",\n      \"pmids\": [\"37933960\", \"36712004\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Functional consequence of the specific phosphorylation site not validated by mutagenesis\",\n        \"Whether phosphorylation regulates complex assembly, localization, or activity unknown\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How CDPK1 phosphorylation of HIP mechanistically controls microneme trafficking and exocytosis, and the structural basis of the HOOK-FTS-HIP complex, remain open.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No phosphomutant analysis linking specific sites to trafficking function\",\n        \"No structural characterization of the complex\",\n        \"Motor/cargo adaptor connecting the complex to micronemes not identified\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0030674\", \"supporting_discovery_ids\": [0], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0020009\", \"supporting_discovery_ids\": [1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0045055\", \"supporting_discovery_ids\": [2, 4], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0006886\", \"supporting_discovery_ids\": [0, 4], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"complexes\": [\n      \"HOOK-FTS-HIP trimeric complex (parasite FHF-like endosomal trafficking complex)\"\n    ],\n    \"partners\": [\n      \"TgHOOK\",\n      \"TgFTS\",\n      \"CDPK1 (kinase acting upstream of HIP)\"\n    ],\n    \"other_free_text\": [\n      \"HIP is a coccidian-specific protein that replaces the FHIP subunit of the conserved eukaryotic FHF complex [#0].\",\n      \"HIP depletion impairs apical microneme positioning, secretion, motility, attachment, invasion, and egress [#2].\"\n    ]\n  },\n  \"strain_conflicts\": []\n}","audit_flag":null,"strains":[{"strain":"ME49","gene_id":"TGME49_306920","name":"HIP","product":"HOOK interacting protein HIP","uniprot_acc":"A0A125YIQ3","chromosome":"TGME49_chrXI","start_pos":183029},{"strain":"GT1","gene_id":"TGGT1_306920","name":null,"product":"hypothetical protein","uniprot_acc":null,"chromosome":"TGGT1_chrXI","start_pos":162761},{"strain":"RH88","gene_id":"TGRH88_048390","name":null,"product":"unspecified product","uniprot_acc":null,"chromosome":"CM023092","start_pos":208851},{"strain":"VEG","gene_id":"TGVEG_306920","name":null,"product":"hypothetical protein","uniprot_acc":"B6KVJ2","chromosome":"TGVEG_chrXI","start_pos":194668}]}