{"gene":"TRAPPC8","run_date":"2026-06-10T10:51:55","timeline":{"discoveries":[{"year":2012,"finding":"Yeast Trs85 (ortholog of TRAPPC8) directly interacts with Atg9 and is a component of Atg9 vesicles; the Trs85-containing TRAPPIII complex facilitates association of the Rab GTPase Ypt1 onto Atg9 vesicles, and both Trs85 and Ypt1 localize to the preautophagosomal structure in an Atg9-dependent manner, implicating TRAPPIII as a vesicle-tethering machinery in autophagosome formation.","method":"Atg9 vesicle purification followed by mass spectrometry, co-immunoprecipitation/direct interaction assay, fluorescence microscopy","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — purification + MS identification, direct interaction assay, and localization studies; replicated across multiple approaches in one study and consistent with earlier genetic findings","pmids":["23129774"],"is_preprint":false},{"year":2005,"finding":"Yeast Trs85 (ortholog of TRAPPC8) is required for biogenesis of Cvt vesicles and organization of the preautophagosomal structure; loss of Trs85 specifically blocks GFP-Atg8 recruitment to the PAS during selective autophagy (Cvt pathway) and reduces bulk autophagy rate, without affecting ER-to-Golgi trafficking or vacuolar biogenesis.","method":"Gene deletion analysis, fluorescence microscopy (GFP-Atg8 localization), electron microscopy, biochemical assays for vacuolar protease maturation","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (EM, fluorescence, biochemistry) in single study; independently replicated in PMID:16874038","pmids":["16079147"],"is_preprint":false},{"year":2005,"finding":"Trs85 (ortholog of TRAPPC8) is required for macroautophagy, pexophagy, and the cytoplasm-to-vacuole targeting (Cvt) pathway in both Yarrowia lipolytica and Saccharomyces cerevisiae, established by parallel genetic screens and deletion analysis in two yeast species.","method":"Forward genetic screen, gene deletion, selective autophagy assays (pexophagy induction, Cvt pathway)","journal":"Autophagy","confidence":"High","confidence_rationale":"Tier 2 / Strong — independently replicated in two yeast species by genetic deletion with defined pathway readouts; consistent with PMID:16079147","pmids":["16874038"],"is_preprint":false},{"year":2014,"finding":"Human TRAPPC8 contains a C-terminal ASH (ASPM-SPD2-Hydin) domain and an N-terminal α-solenoid/TPR-repeat region; endogenous TRAPPC8 localizes to the centrosome/basal body, and its depletion impairs ciliogenesis and blocks GFP-Rabin8 targeting to the centrosome.","method":"Bioinformatic domain prediction, immunofluorescence microscopy of endogenous and exogenous TRAPPC8, siRNA knockdown with ciliogenesis and centrosome-targeting readouts","journal":"Cilia","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization by immunofluorescence with functional KD phenotype (ciliogenesis, Rabin8 targeting), single lab, two orthogonal methods","pmids":["25018876"],"is_preprint":false},{"year":2013,"finding":"TRAPPC8 specifically interacts with HPV L2 capsid protein (central region of TRAPPC8 exposed on the cell surface colocalizes with inoculated pseudovirions); TRAPPC8 knockdown in HeLa and HaCaT cells reduces HPV entry for multiple HPV types independently of L2, and TRAPPC8 loss or L2 over-expression both cause dispersal of the Golgi stack, indicating TRAPPC8 functions in endocytosis and Golgi maintenance required for HPV cell entry.","method":"Co-immunoprecipitation (TRAPPC8–L2 interaction), siRNA knockdown, immunofluorescence microscopy (Golgi morphology, PsV colocalization), reporter gene transduction assay, authentic HPV31 infection assay","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal interaction (Co-IP) plus KD with multiple orthogonal functional readouts (reporter, authentic virus, Golgi morphology), single lab","pmids":["24244674"],"is_preprint":false},{"year":2020,"finding":"TRAPPC8 (TRAPPIII-specific subunit) interacts with the ciliopathy protein OFD1 and is required for the association of OFD1 with pericentriolar material protein PCM1; TRAPPC8 depletion reduces OFD1–PCM1 colocalization without disrupting centriolar satellite structure. Additionally, the TRAPPC8–OFD1 interaction is mutually inhibitory with the TRAPPC12–OFD1 interaction, explaining distinct cilium-length phenotypes upon depletion of each subunit.","method":"Co-immunoprecipitation (TRAPPC8–OFD1, TRAPPC12–OFD1 interactions), siRNA knockdown, immunofluorescence microscopy (OFD1/PCM1 colocalization, centriolar satellite integrity, cilium length)","journal":"Frontiers in cell and developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP plus KD with defined morphological readouts; single lab, two orthogonal methods","pmids":["32258032"],"is_preprint":false},{"year":2025,"finding":"In budding yeast, loss of Trs85 (TRAPPC8 ortholog) suppresses plasma-membrane and cell-wall integrity defects and corrects abnormal endosomal localization of the v-SNARE Snc1 in complex-sphingolipid-deficient cells; overexpression of Ypt1 (regulated by TRAPPIII) exacerbates these defects, placing Trs85/TRAPPIII upstream of Ypt1-mediated vesicular trafficking at endosomes.","method":"Suppressor mutation screen, gene deletion, fluorescence microscopy (yeGFP-Snc1 localization), Ypt1 overexpression epistasis, stress-sensitivity assays","journal":"The FEBS journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis (suppressor screen + Ypt1 OE) with fluorescence localization readout; single lab, multiple orthogonal approaches","pmids":["40266832"],"is_preprint":false}],"current_model":"TRAPPC8 (TRS85/TRAPPIII subunit) functions as a component of the TRAPPIII tethering complex that directly binds Atg9 on autophagy precursor vesicles to recruit the Rab GTPase Ypt1/Rab1 and promote autophagosome formation; in mammalian cells it additionally localizes to the centrosome/basal body via its ASH domain, where it supports ciliogenesis by facilitating OFD1–PCM1 association and Rabin8 centrosome targeting, and it interacts with HPV L2 capsid protein to mediate viral endocytic entry and maintain Golgi integrity."},"narrative":{"mechanistic_narrative":"TRAPPC8 (yeast Trs85) is the TRAPPIII-specific subunit of the multi-subunit TRAPP tethering complex, where it couples membrane vesicle recognition to activation of the Rab GTPase Ypt1/Rab1 to drive autophagosome formation [PMID:23129774, PMID:16079147]. In yeast it directly binds Atg9 and is itself a component of Atg9 vesicles, recruiting Ypt1 onto these vesicles and localizing with Ypt1 to the preautophagosomal structure in an Atg9-dependent manner [PMID:23129774]; consistent with this tethering role, Trs85 is selectively required for macroautophagy, pexophagy, and the cytoplasm-to-vacuole targeting (Cvt) pathway and for organization of the PAS, without affecting ER-to-Golgi trafficking or vacuolar biogenesis [PMID:16079147, PMID:16874038]. Trs85/TRAPPIII acts upstream of Ypt1-mediated vesicular trafficking more broadly, since its loss corrects endosomal mislocalization of the v-SNARE Snc1 and rescues membrane and cell-wall integrity defects in sphingolipid-deficient cells, whereas excess Ypt1 worsens them [PMID:40266832]. In mammalian cells TRAPPC8 carries a C-terminal ASH domain and an N-terminal α-solenoid/TPR region and localizes to the centrosome/basal body, where it supports ciliogenesis by enabling Rabin8 centrosome targeting and by promoting OFD1–PCM1 association, an interaction held in balance with a competing TRAPPC12–OFD1 interaction [PMID:25018876, PMID:32258032]. TRAPPC8 additionally binds the HPV L2 capsid protein and is required for viral endocytic entry and for maintenance of Golgi stack integrity [PMID:24244674].","teleology":[{"year":2005,"claim":"Established that Trs85 is a dedicated autophagy factor rather than a general secretion component, defining the entry point for TRAPP function in selective and bulk autophagy.","evidence":"Gene deletion with GFP-Atg8 localization, electron microscopy, and vacuolar protease maturation assays in yeast, plus parallel genetic screens in two yeast species","pmids":["16079147","16874038"],"confidence":"High","gaps":["Molecular partner on the vesicle not yet identified","Did not define which Rab Trs85 acts through","No structural basis for autophagy-specific function"]},{"year":2012,"claim":"Resolved the molecular mechanism by which Trs85 acts in autophagy: it binds Atg9 directly and recruits the Rab Ypt1 onto Atg9 vesicles, establishing TRAPPIII as a vesicle-tethering machinery for autophagosome formation.","evidence":"Atg9 vesicle purification with mass spectrometry, direct interaction/co-immunoprecipitation assays, and fluorescence localization in yeast","pmids":["23129774"],"confidence":"High","gaps":["Structure of the Trs85-Atg9 interface not determined","Mechanism of Ypt1 nucleotide exchange by TRAPPIII not dissected here","Conservation of the Atg9 interaction in mammalian TRAPPC8 untested"]},{"year":2013,"claim":"Extended TRAPPC8 function beyond autophagy by showing it mediates HPV endocytic entry and maintains Golgi integrity in human cells.","evidence":"Co-IP of TRAPPC8–L2, siRNA knockdown with reporter transduction and authentic HPV31 infection, and Golgi morphology imaging in HeLa/HaCaT cells","pmids":["24244674"],"confidence":"Medium","gaps":["Whether the L2 interaction reflects TRAPP complex function or a moonlighting role unclear","How TRAPPC8 loss disperses the Golgi mechanistically not defined","Single lab; surface exposure of TRAPPC8 not independently confirmed"]},{"year":2014,"claim":"Defined the domain architecture of human TRAPPC8 and placed it at the centrosome/basal body, linking it to ciliogenesis through Rabin8 targeting.","evidence":"Bioinformatic domain prediction, immunofluorescence of endogenous/exogenous protein, and siRNA knockdown with ciliogenesis and Rabin8-targeting readouts","pmids":["25018876"],"confidence":"Medium","gaps":["Direct binding partner at the centrosome not identified","Role of the ASH domain in localization not functionally tested","Single-lab observation"]},{"year":2020,"claim":"Provided a mechanism for TRAPPC8's ciliary role: it promotes OFD1–PCM1 association and competes with TRAPPC12 for OFD1 binding, explaining subunit-specific cilium-length phenotypes.","evidence":"Reciprocal Co-IP (TRAPPC8–OFD1, TRAPPC12–OFD1), siRNA knockdown, and immunofluorescence of OFD1/PCM1 colocalization and cilium length","pmids":["32258032"],"confidence":"Medium","gaps":["Structural basis of the mutually inhibitory OFD1 binding not resolved","Whether this requires intact TRAPP complex unknown","Single lab"]},{"year":2025,"claim":"Positioned Trs85/TRAPPIII upstream of Ypt1-dependent trafficking at endosomes, broadening its role beyond autophagosome formation to membrane and cell-wall homeostasis.","evidence":"Suppressor screen, gene deletion, yeGFP-Snc1 localization, Ypt1 overexpression epistasis, and stress-sensitivity assays in yeast","pmids":["40266832"],"confidence":"Medium","gaps":["Direct molecular target at the endosome not identified","Relevance of this endosomal role to mammalian TRAPPC8 untested","Single lab"]},{"year":null,"claim":"Whether the autophagy/Atg9-tethering, ciliary/centrosomal, and HPV-entry functions of TRAPPC8 reflect a single TRAPPIII-dependent activity or distinct moonlighting roles remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of human TRAPPC8 within TRAPPIII","Direct mammalian Atg9 interaction not demonstrated","Mechanism connecting Golgi maintenance, ciliogenesis, and autophagy unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,6]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,5]}],"localization":[{"term_id":"GO:0005815","term_label":"microtubule organizing center","supporting_discovery_ids":[3,5]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[0]}],"pathway":[{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[0,1,2]},{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[0,6]}],"complexes":["TRAPPIII"],"partners":["ATG9","YPT1","OFD1","TRAPPC12","RABIN8","PCM1","HPV L2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9Y2L5","full_name":"Trafficking protein particle complex subunit 8","aliases":["Protein TRS85 homolog"],"length_aa":1435,"mass_kda":161.0,"function":"Plays a role in endoplasmic reticulum to Golgi apparatus trafficking at a very early stage (PubMed:21525244). Maintains together with TBC1D14 the cycling pool of ATG9 required for initiation of autophagy (PubMed:26711178). Involved in collagen secretion (PubMed:32095531)","subcellular_location":"Golgi apparatus, cis-Golgi network","url":"https://www.uniprot.org/uniprotkb/Q9Y2L5/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/TRAPPC8","classification":"Common Essential","n_dependent_lines":1192,"n_total_lines":1208,"dependency_fraction":0.9867549668874173},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"TRAPPC1","stoichiometry":10.0},{"gene":"TRAPPC11","stoichiometry":10.0},{"gene":"TRAPPC2","stoichiometry":10.0},{"gene":"ACTR2","stoichiometry":0.2},{"gene":"ARL3","stoichiometry":0.2},{"gene":"ARL8B","stoichiometry":0.2},{"gene":"KRAS","stoichiometry":0.2},{"gene":"MIS12","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/TRAPPC8","total_profiled":1310},"omim":[{"mim_id":"614781","title":"TECTONIN BETA-PROPELLER REPEAT-CONTAINING 1; TECPR1","url":"https://www.omim.org/entry/614781"},{"mim_id":"614136","title":"TRAFFICKING PROTEIN PARTICLE COMPLEX, SUBUNIT 8; TRAPPC8","url":"https://www.omim.org/entry/614136"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"},{"location":"Microtubules","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/TRAPPC8"},"hgnc":{"alias_symbol":["HsT2706","TRS85","GSG1"],"prev_symbol":["KIAA1012"]},"alphafold":{"accession":"Q9Y2L5","domains":[{"cath_id":"3.40.50,3.40.50","chopping":"2-80_144-234_338-379","consensus_level":"medium","plddt":89.6565,"start":2,"end":379},{"cath_id":"2.60.40,2.60.40","chopping":"670-681_736-785_800-848_868-909","consensus_level":"high","plddt":90.8906,"start":670,"end":909},{"cath_id":"2.60.40.10","chopping":"1304-1435","consensus_level":"high","plddt":78.5443,"start":1304,"end":1435},{"cath_id":"1.20.58","chopping":"412-517","consensus_level":"medium","plddt":90.6266,"start":412,"end":517}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y2L5","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y2L5-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y2L5-F1-predicted_aligned_error_v6.png","plddt_mean":78.94},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TRAPPC8","jax_strain_url":"https://www.jax.org/strain/search?query=TRAPPC8"},"sequence":{"accession":"Q9Y2L5","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9Y2L5.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9Y2L5/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y2L5"}},"corpus_meta":[{"pmid":"23129774","id":"PMC_23129774","title":"Atg9 vesicles recruit vesicle-tethering proteins Trs85 and Ypt1 to the autophagosome formation site.","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/23129774","citation_count":95,"is_preprint":false},{"pmid":"16079147","id":"PMC_16079147","title":"Trs85 (Gsg1), a component of the TRAPP complexes, is required for the organization of the preautophagosomal structure during selective autophagy via the Cvt pathway.","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16079147","citation_count":82,"is_preprint":false},{"pmid":"16874038","id":"PMC_16874038","title":"Trs85 is required for macroautophagy, pexophagy and cytoplasm to vacuole targeting in Yarrowia lipolytica and Saccharomyces cerevisiae.","date":"2005","source":"Autophagy","url":"https://pubmed.ncbi.nlm.nih.gov/16874038","citation_count":61,"is_preprint":false},{"pmid":"25018876","id":"PMC_25018876","title":"Identification of conserved, centrosome-targeting ASH domains in TRAPPII complex subunits and TRAPPC8.","date":"2014","source":"Cilia","url":"https://pubmed.ncbi.nlm.nih.gov/25018876","citation_count":33,"is_preprint":false},{"pmid":"24244674","id":"PMC_24244674","title":"Identification of TRAPPC8 as a host factor required for human papillomavirus cell entry.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/24244674","citation_count":15,"is_preprint":false},{"pmid":"32258032","id":"PMC_32258032","title":"Distinct Roles of TRAPPC8 and TRAPPC12 in Ciliogenesis via Their Interactions With OFD1.","date":"2020","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/32258032","citation_count":9,"is_preprint":false},{"pmid":"37771153","id":"PMC_37771153","title":"SP-141 targets Trs85 to inhibit rice blast fungus infection and functions as a potential broad-spectrum antifungal agent.","date":"2023","source":"Plant communications","url":"https://pubmed.ncbi.nlm.nih.gov/37771153","citation_count":8,"is_preprint":false},{"pmid":"40266832","id":"PMC_40266832","title":"TRS85 and LEM3 suppressor mutations rescue stress hypersensitivities caused by lack of structural diversity of complex sphingolipids in budding yeast.","date":"2025","source":"The FEBS journal","url":"https://pubmed.ncbi.nlm.nih.gov/40266832","citation_count":4,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":6263,"output_tokens":2106,"usd":0.02519,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9112,"output_tokens":3008,"usd":0.06038,"stage2_stop_reason":"end_turn"},"total_usd":0.08557,"stage1_batch_id":"msgbatch_017qqVz33Ga63SCDwzb35XPb","stage2_batch_id":"msgbatch_01Scr2Ei9x4HJMiRGxwrmvLK","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2012,\n      \"finding\": \"Yeast Trs85 (ortholog of TRAPPC8) directly interacts with Atg9 and is a component of Atg9 vesicles; the Trs85-containing TRAPPIII complex facilitates association of the Rab GTPase Ypt1 onto Atg9 vesicles, and both Trs85 and Ypt1 localize to the preautophagosomal structure in an Atg9-dependent manner, implicating TRAPPIII as a vesicle-tethering machinery in autophagosome formation.\",\n      \"method\": \"Atg9 vesicle purification followed by mass spectrometry, co-immunoprecipitation/direct interaction assay, fluorescence microscopy\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — purification + MS identification, direct interaction assay, and localization studies; replicated across multiple approaches in one study and consistent with earlier genetic findings\",\n      \"pmids\": [\"23129774\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Yeast Trs85 (ortholog of TRAPPC8) is required for biogenesis of Cvt vesicles and organization of the preautophagosomal structure; loss of Trs85 specifically blocks GFP-Atg8 recruitment to the PAS during selective autophagy (Cvt pathway) and reduces bulk autophagy rate, without affecting ER-to-Golgi trafficking or vacuolar biogenesis.\",\n      \"method\": \"Gene deletion analysis, fluorescence microscopy (GFP-Atg8 localization), electron microscopy, biochemical assays for vacuolar protease maturation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (EM, fluorescence, biochemistry) in single study; independently replicated in PMID:16874038\",\n      \"pmids\": [\"16079147\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Trs85 (ortholog of TRAPPC8) is required for macroautophagy, pexophagy, and the cytoplasm-to-vacuole targeting (Cvt) pathway in both Yarrowia lipolytica and Saccharomyces cerevisiae, established by parallel genetic screens and deletion analysis in two yeast species.\",\n      \"method\": \"Forward genetic screen, gene deletion, selective autophagy assays (pexophagy induction, Cvt pathway)\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — independently replicated in two yeast species by genetic deletion with defined pathway readouts; consistent with PMID:16079147\",\n      \"pmids\": [\"16874038\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Human TRAPPC8 contains a C-terminal ASH (ASPM-SPD2-Hydin) domain and an N-terminal α-solenoid/TPR-repeat region; endogenous TRAPPC8 localizes to the centrosome/basal body, and its depletion impairs ciliogenesis and blocks GFP-Rabin8 targeting to the centrosome.\",\n      \"method\": \"Bioinformatic domain prediction, immunofluorescence microscopy of endogenous and exogenous TRAPPC8, siRNA knockdown with ciliogenesis and centrosome-targeting readouts\",\n      \"journal\": \"Cilia\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization by immunofluorescence with functional KD phenotype (ciliogenesis, Rabin8 targeting), single lab, two orthogonal methods\",\n      \"pmids\": [\"25018876\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"TRAPPC8 specifically interacts with HPV L2 capsid protein (central region of TRAPPC8 exposed on the cell surface colocalizes with inoculated pseudovirions); TRAPPC8 knockdown in HeLa and HaCaT cells reduces HPV entry for multiple HPV types independently of L2, and TRAPPC8 loss or L2 over-expression both cause dispersal of the Golgi stack, indicating TRAPPC8 functions in endocytosis and Golgi maintenance required for HPV cell entry.\",\n      \"method\": \"Co-immunoprecipitation (TRAPPC8–L2 interaction), siRNA knockdown, immunofluorescence microscopy (Golgi morphology, PsV colocalization), reporter gene transduction assay, authentic HPV31 infection assay\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal interaction (Co-IP) plus KD with multiple orthogonal functional readouts (reporter, authentic virus, Golgi morphology), single lab\",\n      \"pmids\": [\"24244674\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TRAPPC8 (TRAPPIII-specific subunit) interacts with the ciliopathy protein OFD1 and is required for the association of OFD1 with pericentriolar material protein PCM1; TRAPPC8 depletion reduces OFD1–PCM1 colocalization without disrupting centriolar satellite structure. Additionally, the TRAPPC8–OFD1 interaction is mutually inhibitory with the TRAPPC12–OFD1 interaction, explaining distinct cilium-length phenotypes upon depletion of each subunit.\",\n      \"method\": \"Co-immunoprecipitation (TRAPPC8–OFD1, TRAPPC12–OFD1 interactions), siRNA knockdown, immunofluorescence microscopy (OFD1/PCM1 colocalization, centriolar satellite integrity, cilium length)\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP plus KD with defined morphological readouts; single lab, two orthogonal methods\",\n      \"pmids\": [\"32258032\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In budding yeast, loss of Trs85 (TRAPPC8 ortholog) suppresses plasma-membrane and cell-wall integrity defects and corrects abnormal endosomal localization of the v-SNARE Snc1 in complex-sphingolipid-deficient cells; overexpression of Ypt1 (regulated by TRAPPIII) exacerbates these defects, placing Trs85/TRAPPIII upstream of Ypt1-mediated vesicular trafficking at endosomes.\",\n      \"method\": \"Suppressor mutation screen, gene deletion, fluorescence microscopy (yeGFP-Snc1 localization), Ypt1 overexpression epistasis, stress-sensitivity assays\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis (suppressor screen + Ypt1 OE) with fluorescence localization readout; single lab, multiple orthogonal approaches\",\n      \"pmids\": [\"40266832\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TRAPPC8 (TRS85/TRAPPIII subunit) functions as a component of the TRAPPIII tethering complex that directly binds Atg9 on autophagy precursor vesicles to recruit the Rab GTPase Ypt1/Rab1 and promote autophagosome formation; in mammalian cells it additionally localizes to the centrosome/basal body via its ASH domain, where it supports ciliogenesis by facilitating OFD1–PCM1 association and Rabin8 centrosome targeting, and it interacts with HPV L2 capsid protein to mediate viral endocytic entry and maintain Golgi integrity.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TRAPPC8 (yeast Trs85) is the TRAPPIII-specific subunit of the multi-subunit TRAPP tethering complex, where it couples membrane vesicle recognition to activation of the Rab GTPase Ypt1/Rab1 to drive autophagosome formation [#0, #1]. In yeast it directly binds Atg9 and is itself a component of Atg9 vesicles, recruiting Ypt1 onto these vesicles and localizing with Ypt1 to the preautophagosomal structure in an Atg9-dependent manner [#0]; consistent with this tethering role, Trs85 is selectively required for macroautophagy, pexophagy, and the cytoplasm-to-vacuole targeting (Cvt) pathway and for organization of the PAS, without affecting ER-to-Golgi trafficking or vacuolar biogenesis [#1, #2]. Trs85/TRAPPIII acts upstream of Ypt1-mediated vesicular trafficking more broadly, since its loss corrects endosomal mislocalization of the v-SNARE Snc1 and rescues membrane and cell-wall integrity defects in sphingolipid-deficient cells, whereas excess Ypt1 worsens them [#6]. In mammalian cells TRAPPC8 carries a C-terminal ASH domain and an N-terminal \\u03b1-solenoid/TPR region and localizes to the centrosome/basal body, where it supports ciliogenesis by enabling Rabin8 centrosome targeting and by promoting OFD1\\u2013PCM1 association, an interaction held in balance with a competing TRAPPC12\\u2013OFD1 interaction [#3, #5]. TRAPPC8 additionally binds the HPV L2 capsid protein and is required for viral endocytic entry and for maintenance of Golgi stack integrity [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 2005,\n      \"claim\": \"Established that Trs85 is a dedicated autophagy factor rather than a general secretion component, defining the entry point for TRAPP function in selective and bulk autophagy.\",\n      \"evidence\": \"Gene deletion with GFP-Atg8 localization, electron microscopy, and vacuolar protease maturation assays in yeast, plus parallel genetic screens in two yeast species\",\n      \"pmids\": [\n        \"16079147\",\n        \"16874038\"\n      ],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Molecular partner on the vesicle not yet identified\",\n        \"Did not define which Rab Trs85 acts through\",\n        \"No structural basis for autophagy-specific function\"\n      ]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Resolved the molecular mechanism by which Trs85 acts in autophagy: it binds Atg9 directly and recruits the Rab Ypt1 onto Atg9 vesicles, establishing TRAPPIII as a vesicle-tethering machinery for autophagosome formation.\",\n      \"evidence\": \"Atg9 vesicle purification with mass spectrometry, direct interaction/co-immunoprecipitation assays, and fluorescence localization in yeast\",\n      \"pmids\": [\n        \"23129774\"\n      ],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structure of the Trs85-Atg9 interface not determined\",\n        \"Mechanism of Ypt1 nucleotide exchange by TRAPPIII not dissected here\",\n        \"Conservation of the Atg9 interaction in mammalian TRAPPC8 untested\"\n      ]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Extended TRAPPC8 function beyond autophagy by showing it mediates HPV endocytic entry and maintains Golgi integrity in human cells.\",\n      \"evidence\": \"Co-IP of TRAPPC8\\u2013L2, siRNA knockdown with reporter transduction and authentic HPV31 infection, and Golgi morphology imaging in HeLa/HaCaT cells\",\n      \"pmids\": [\n        \"24244674\"\n      ],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether the L2 interaction reflects TRAPP complex function or a moonlighting role unclear\",\n        \"How TRAPPC8 loss disperses the Golgi mechanistically not defined\",\n        \"Single lab; surface exposure of TRAPPC8 not independently confirmed\"\n      ]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Defined the domain architecture of human TRAPPC8 and placed it at the centrosome/basal body, linking it to ciliogenesis through Rabin8 targeting.\",\n      \"evidence\": \"Bioinformatic domain prediction, immunofluorescence of endogenous/exogenous protein, and siRNA knockdown with ciliogenesis and Rabin8-targeting readouts\",\n      \"pmids\": [\n        \"25018876\"\n      ],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct binding partner at the centrosome not identified\",\n        \"Role of the ASH domain in localization not functionally tested\",\n        \"Single-lab observation\"\n      ]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Provided a mechanism for TRAPPC8's ciliary role: it promotes OFD1\\u2013PCM1 association and competes with TRAPPC12 for OFD1 binding, explaining subunit-specific cilium-length phenotypes.\",\n      \"evidence\": \"Reciprocal Co-IP (TRAPPC8\\u2013OFD1, TRAPPC12\\u2013OFD1), siRNA knockdown, and immunofluorescence of OFD1/PCM1 colocalization and cilium length\",\n      \"pmids\": [\n        \"32258032\"\n      ],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Structural basis of the mutually inhibitory OFD1 binding not resolved\",\n        \"Whether this requires intact TRAPP complex unknown\",\n        \"Single lab\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Positioned Trs85/TRAPPIII upstream of Ypt1-dependent trafficking at endosomes, broadening its role beyond autophagosome formation to membrane and cell-wall homeostasis.\",\n      \"evidence\": \"Suppressor screen, gene deletion, yeGFP-Snc1 localization, Ypt1 overexpression epistasis, and stress-sensitivity assays in yeast\",\n      \"pmids\": [\n        \"40266832\"\n      ],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct molecular target at the endosome not identified\",\n        \"Relevance of this endosomal role to mammalian TRAPPC8 untested\",\n        \"Single lab\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Whether the autophagy/Atg9-tethering, ciliary/centrosomal, and HPV-entry functions of TRAPPC8 reflect a single TRAPPIII-dependent activity or distinct moonlighting roles remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No structure of human TRAPPC8 within TRAPPIII\",\n        \"Direct mammalian Atg9 interaction not demonstrated\",\n        \"Mechanism connecting Golgi maintenance, ciliogenesis, and autophagy unknown\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\n        \"term_id\": \"GO:0098772\",\n        \"supporting_discovery_ids\": [\n          0,\n          6\n        ]\n      },\n      {\n        \"term_id\": \"GO:0060090\",\n        \"supporting_discovery_ids\": [\n          0,\n          5\n        ]\n      }\n    ],\n    \"localization\": [\n      {\n        \"term_id\": \"GO:0005815\",\n        \"supporting_discovery_ids\": [\n          3,\n          5\n        ]\n      },\n      {\n        \"term_id\": \"GO:0031410\",\n        \"supporting_discovery_ids\": [\n          0\n        ]\n      }\n    ],\n    \"pathway\": [\n      {\n        \"term_id\": \"R-HSA-9612973\",\n        \"supporting_discovery_ids\": [\n          0,\n          1,\n          2\n        ]\n      },\n      {\n        \"term_id\": \"R-HSA-5653656\",\n        \"supporting_discovery_ids\": [\n          0,\n          6\n        ]\n      }\n    ],\n    \"complexes\": [\n      \"TRAPPIII\"\n    ],\n    \"partners\": [\n      \"Atg9\",\n      \"Ypt1\",\n      \"OFD1\",\n      \"TRAPPC12\",\n      \"Rabin8\",\n      \"PCM1\",\n      \"HPV L2\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":4,"faith_total":5,"faith_pct":80.0}}