{"gene":"TRAPPC2L","run_date":"2026-06-10T10:51:55","timeline":{"discoveries":[{"year":2009,"finding":"TRAPPC2L physically interacts with TRAPP complex components and co-fractionates with a portion of cellular TRAPP on very low-density membranes, distinct from the Golgi-associated TRAPP pool. RNAi-mediated knockdown of TRAPPC2L in HeLa cells causes Golgi fragmentation, implicating it in Golgi dynamics. Yeast complementation studies showed TRAPPC2L and TRAPPC2 are functionally distinct despite sequence relatedness.","method":"Gradient fractionation of cellular membranes, RNA interference knockdown with Golgi morphology readout, yeast complementation assays","journal":"Traffic (Copenhagen, Denmark)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (fractionation, RNAi phenotype, yeast complementation) in a single lab study","pmids":["19416478"],"is_preprint":false},{"year":2018,"finding":"A missense variant p.Asp37Tyr in TRAPPC2L abolishes the interaction between TRAPPC2L and TRAPPC10/Trs130 (a TRAPP II component), as shown by yeast two-hybrid analysis. Patient fibroblasts showed specific membrane trafficking delays and elevated levels of active RAB11, linking TRAPPC2L to TRAPP II-mediated RAB11 GEF activity.","method":"Yeast two-hybrid analysis, membrane trafficking assays in patient fibroblasts, RAB11 activation assays","journal":"Journal of medical genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal interaction mapping by Y2H and cell biological trafficking assays, single lab with two orthogonal methods","pmids":["30120216"],"is_preprint":false},{"year":2020,"finding":"A second missense variant p.Ala2Gly in TRAPPC2L disrupts its interaction with TRAPPC6a (another core TRAPP protein), as demonstrated by yeast two-hybrid assay and in vitro binding, while the p.Asp37Tyr variant does not affect this interaction. Size exclusion chromatography indicated the p.Ala2Gly variant affects overall TRAPP complex assembly. Both variants increased active RAB11 levels in patient fibroblasts and caused membrane trafficking delays into and out of the Golgi, positioning TRAPPC2L as a putative adaptor for other TRAPP subunits.","method":"Yeast two-hybrid assay, in vitro binding assay, size exclusion chromatography, membrane trafficking assays in patient fibroblasts, RAB11 activation assays","journal":"Journal of medical genetics","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — in vitro binding and Y2H for interaction, SEC for complex assembly, cell biological assays for trafficking, multiple orthogonal methods in one study","pmids":["32843486"],"is_preprint":false},{"year":2019,"finding":"In Aspergillus nidulans, the TRAPPC2L ortholog Tca17 binds to the 'Trs33 side' of the TRAPP core and recruits TRAPPC11, TRAPPC12, and TRAPPC13 subunits to form TRAPPIII. Additionally, Tca17 participates in a stable TRAPPII-specific subcomplex with Trs120/Trs130/Trs65, and its incorporation into core TRAPP (via Trs20 and Trs33) generates TRAPPII. This positions TRAPPC2L as a structural scaffold/adaptor in both TRAPPII and TRAPPIII assembly.","method":"Size-fractionation chromatography, single-step purification coupled to mass spectrometry, negative-stain electron microscopy, genetic epistasis using constitutively active RAB alleles","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — biochemical purification with MS, EM structural analysis, and genetic epistasis in multiple orthogonal experiments","pmids":["31869332"],"is_preprint":false},{"year":2022,"finding":"Mutant TRAPPC10 variants weaken the interaction between TRAPPC10 and its putative adaptor protein TRAPPC2L, as demonstrated by molecular interaction studies. This establishes TRAPPC2L as an adaptor bridging TRAPPC10 into the TRAPP II complex.","method":"Molecular interaction/binding studies between mutant TRAPPC10 and TRAPPC2L","journal":"PLoS genetics","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — interaction studies described in abstract without full methodological detail, single lab","pmids":["35298461"],"is_preprint":false},{"year":2024,"finding":"Human TRAPPC2L can functionally replace its yeast ortholog (Tca17) in Saccharomyces cerevisiae, demonstrating sufficient conservation of function for humanized yeast complementation. This confirms TRAPPC2L as a genuine ortholog of yeast Tca17 with conserved TRAPP-related function.","method":"Humanized yeast complementation using CRISPR/Cas9 scar-less editing to replace yeast subunit with human TRAPPC2L","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct genetic complementation in yeast, single study with clean functional readout","pmids":["39273027"],"is_preprint":false},{"year":2025,"finding":"Knockout of Trappc2l in male mice causes complete male infertility without developmental abnormalities in other tissues. Histological examination revealed formation of germ cell syncytial structures with multiple nuclei starting at embryonic day E17.5, with complete germ cell loss by 2 weeks postnatally. The syncytia arise from abnormal cell division (not cell fusion), and meiosis-associated genes Stra8 and Sycp3 are aberrantly expressed in embryonic Trappc2l-deficient germ cells, indicating TRAPPC2L is required for maintaining mitotic quiescence in male germ cells.","method":"Trappc2l knockout mouse model, histological examination, marker gene expression analysis (Stra8, Sycp3), cell division vs. fusion discrimination assays","journal":"Cell proliferation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO mouse model with specific cellular phenotype and mechanistic follow-up, single lab","pmids":["40539230"],"is_preprint":false}],"current_model":"TRAPPC2L is a core subunit of the TRAPP complex that functions as a structural adaptor: it interacts with TRAPPC6a and TRAPPC10 to scaffold TRAPP II assembly, and its ortholog Tca17 in fungi recruits TRAPPC11/12/13 into TRAPPIII; loss-of-function or disease-associated missense variants disrupt these interactions, impair membrane trafficking through the Golgi, and elevate active RAB11 levels, while in vivo knockout in mice additionally reveals an essential role in maintaining mitotic quiescence of male germ cells."},"narrative":{"mechanistic_narrative":"TRAPPC2L is a core subunit of the multimeric TRAPP complex that acts as a structural adaptor coordinating TRAPP assembly and Golgi-associated membrane trafficking [PMID:19416478, PMID:32843486]. It physically interacts with TRAPP components and partitions in part to a low-density membrane pool distinct from the Golgi-associated TRAPP, and its depletion fragments the Golgi, establishing a role in Golgi dynamics [PMID:19416478]. Mechanistically, TRAPPC2L bridges specific TRAPP subunits into higher-order complexes: it binds TRAPPC6a and TRAPPC10/Trs130 to support TRAPP II assembly [PMID:30120216, PMID:32843486, PMID:35298461], and the conserved yeast/fungal ortholog Tca17 docks on the Trs33 side of the TRAPP core to recruit TRAPPC11/12/13 into TRAPPIII and to generate the TRAPPII-specific subcomplex, marking TRAPPC2L as a scaffold for both TRAPPII and TRAPPIII [PMID:31869332]; human TRAPPC2L functionally substitutes for yeast Tca17, confirming conserved function [PMID:39273027]. Disease-associated missense variants act through this adaptor function: p.Asp37Tyr abolishes TRAPPC2L–TRAPPC10 binding while p.Ala2Gly disrupts TRAPPC2L–TRAPPC6a binding and perturbs overall complex assembly, and both delay trafficking into and out of the Golgi and elevate levels of active RAB11 in patient fibroblasts, linking TRAPPC2L to TRAPP II–dependent RAB11 GEF activity [PMID:30120216, PMID:32843486]. Beyond trafficking, knockout of Trappc2l in mice causes male infertility through formation of multinucleate germ cell syncytia arising from abnormal cell division and aberrant expression of meiotic genes Stra8 and Sycp3, identifying an essential role in maintaining mitotic quiescence of male germ cells [PMID:40539230].","teleology":[{"year":2009,"claim":"Established that TRAPPC2L is a bona fide TRAPP-associated protein with a distinct membrane pool and a functional requirement in Golgi maintenance, separating it from its sequence relative TRAPPC2.","evidence":"Membrane gradient fractionation, RNAi knockdown with Golgi morphology readout, and yeast complementation in HeLa cells","pmids":["19416478"],"confidence":"Medium","gaps":["Specific TRAPP subunit contacts not mapped","Molecular basis of the low-density membrane pool unknown","No link to a downstream GTPase yet"]},{"year":2018,"claim":"Connected TRAPPC2L to TRAPP II function and RAB11 regulation by showing a disease missense variant abolishes binding to TRAPPC10 and elevates active RAB11.","evidence":"Yeast two-hybrid interaction mapping, trafficking assays and RAB11 activation assays in patient fibroblasts","pmids":["30120216"],"confidence":"Medium","gaps":["Whether TRAPPC2L directly modulates GEF activity vs. complex integrity unresolved","Single variant tested","Structural basis of the TRAPPC10 contact not defined"]},{"year":2019,"claim":"Defined TRAPPC2L's ortholog Tca17 as a structural scaffold positioned on the Trs33 side of the TRAPP core that drives both TRAPPIII and TRAPPII assembly, providing the mechanistic basis for its adaptor role.","evidence":"Size-fractionation chromatography, single-step purification with mass spectrometry, negative-stain EM, and genetic epistasis with constitutively active RAB alleles in Aspergillus nidulans","pmids":["31869332"],"confidence":"High","gaps":["Direct extrapolation of fungal architecture to human complexes not demonstrated","High-resolution structure of the human complex absent"]},{"year":2020,"claim":"Distinguished two adaptor contacts by showing p.Ala2Gly disrupts TRAPPC6a binding and overall complex assembly whereas p.Asp37Tyr does not, refining TRAPPC2L as a multi-interface adaptor in TRAPP assembly.","evidence":"Yeast two-hybrid and in vitro binding assays, size exclusion chromatography, and trafficking/RAB11 assays in patient fibroblasts","pmids":["32843486"],"confidence":"High","gaps":["Quantitative contribution of each contact to GEF output not measured","Tissue-level consequences of assembly defects unclear"]},{"year":2022,"claim":"Reinforced the TRAPPC2L–TRAPPC10 bridging model by showing mutant TRAPPC10 weakens the interaction, framing TRAPPC2L as the adaptor incorporating TRAPPC10 into TRAPP II.","evidence":"Molecular interaction/binding studies between mutant TRAPPC10 and TRAPPC2L","pmids":["35298461"],"confidence":"Medium","gaps":["Methodological detail limited","Reciprocal validation and stoichiometry not reported"]},{"year":2024,"claim":"Confirmed functional conservation by demonstrating human TRAPPC2L can replace yeast Tca17, validating cross-species mechanistic inferences.","evidence":"Humanized yeast complementation via CRISPR/Cas9 scar-less subunit replacement","pmids":["39273027"],"confidence":"Medium","gaps":["Complementation does not resolve which human-specific contacts are essential","Quantitative fitness of humanized strain not detailed"]},{"year":2025,"claim":"Revealed an in vivo role beyond trafficking, showing TRAPPC2L is required to maintain mitotic quiescence of male germ cells, with loss causing syncytia and infertility.","evidence":"Trappc2l knockout mouse, histology, Stra8/Sycp3 marker expression, and cell division vs. fusion discrimination","pmids":["40539230"],"confidence":"Medium","gaps":["Mechanistic link between TRAPP trafficking function and germ cell quiescence unknown","Whether the phenotype is RAB11-dependent untested","Role in female germline not addressed"]},{"year":null,"claim":"How TRAPPC2L's adaptor/assembly role mechanistically connects to RAB11 GEF activity and to germ cell mitotic quiescence remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of the human TRAPP complex with TRAPPC2L","Causal pathway from trafficking defect to germ cell division phenotype unmapped","Direct demonstration of GEF modulation by TRAPPC2L lacking"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,2,3,4]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[3]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[0,2]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[0,1,2]}],"complexes":["TRAPP II","TRAPP III"],"partners":["TRAPPC10","TRAPPC6A","TRAPPC11","TRAPPC12","TRAPPC13","RAB11"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9UL33","full_name":"Trafficking protein particle complex subunit 2-like protein","aliases":[],"length_aa":140,"mass_kda":16.1,"function":"Plays a role in vesicular transport from endoplasmic reticulum to Golgi","subcellular_location":"Cytoplasm, perinuclear region; Endoplasmic reticulum; Golgi apparatus","url":"https://www.uniprot.org/uniprotkb/Q9UL33/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/TRAPPC2L","classification":"Not Classified","n_dependent_lines":211,"n_total_lines":1208,"dependency_fraction":0.17466887417218543},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"TRAPPC1","stoichiometry":10.0},{"gene":"TRAPPC2","stoichiometry":10.0},{"gene":"TRAPPC11","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/TRAPPC2L","total_profiled":1310},"omim":[{"mim_id":"620027","title":"NEURODEVELOPMENTAL DISORDER WITH MICROCEPHALY, SHORT STATURE, AND SPEECH DELAY; NEDMISS","url":"https://www.omim.org/entry/620027"},{"mim_id":"618331","title":"ENCEPHALOPATHY, PROGRESSIVE, EARLY-ONSET, WITH EPISODIC RHABDOMYOLYSIS; PEERB","url":"https://www.omim.org/entry/618331"},{"mim_id":"614781","title":"TECTONIN BETA-PROPELLER REPEAT-CONTAINING 1; TECPR1","url":"https://www.omim.org/entry/614781"},{"mim_id":"614139","title":"TRAFFICKING PROTEIN PARTICLE COMPLEX, SUBUNIT 12; TRAPPC12","url":"https://www.omim.org/entry/614139"},{"mim_id":"614138","title":"TRAFFICKING PROTEIN PARTICLE COMPLEX, SUBUNIT 11; TRAPPC11","url":"https://www.omim.org/entry/614138"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Vesicles","reliability":"Supported"},{"location":"Cytosol","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/TRAPPC2L"},"hgnc":{"alias_symbol":["HSPC176"],"prev_symbol":[]},"alphafold":{"accession":"Q9UL33","domains":[{"cath_id":"3.30.450.70","chopping":"1-134","consensus_level":"high","plddt":92.6031,"start":1,"end":134}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UL33","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UL33-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UL33-F1-predicted_aligned_error_v6.png","plddt_mean":91.88},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TRAPPC2L","jax_strain_url":"https://www.jax.org/strain/search?query=TRAPPC2L"},"sequence":{"accession":"Q9UL33","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9UL33.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9UL33/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UL33"}},"corpus_meta":[{"pmid":"19416478","id":"PMC_19416478","title":"TRAPPC2L is a novel, highly conserved TRAPP-interacting protein.","date":"2009","source":"Traffic (Copenhagen, Denmark)","url":"https://pubmed.ncbi.nlm.nih.gov/19416478","citation_count":49,"is_preprint":false},{"pmid":"30120216","id":"PMC_30120216","title":"Bi-allelic mutations in TRAPPC2L result in a neurodevelopmental disorder and have an impact on RAB11 in fibroblasts.","date":"2018","source":"Journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30120216","citation_count":36,"is_preprint":false},{"pmid":"31845298","id":"PMC_31845298","title":"Overlapping genetic architecture between Parkinson disease and melanoma.","date":"2019","source":"Acta neuropathologica","url":"https://pubmed.ncbi.nlm.nih.gov/31845298","citation_count":27,"is_preprint":false},{"pmid":"31869332","id":"PMC_31869332","title":"Characterization of Aspergillus nidulans TRAPPs uncovers unprecedented similarities between fungi and metazoans and reveals the modular assembly of TRAPPII.","date":"2019","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/31869332","citation_count":23,"is_preprint":false},{"pmid":"35298461","id":"PMC_35298461","title":"Biallelic variants in TRAPPC10 cause a microcephalic TRAPPopathy disorder in humans and mice.","date":"2022","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/35298461","citation_count":17,"is_preprint":false},{"pmid":"36266402","id":"PMC_36266402","title":"Epigenetic impact of a 1-week intensive multimodal group program for adolescents with multiple adverse childhood experiences.","date":"2022","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/36266402","citation_count":16,"is_preprint":false},{"pmid":"24654229","id":"PMC_24654229","title":"Slow overmethylation of housekeeping genes in the body mucosa is associated with the risk for gastric cancer.","date":"2014","source":"Cancer prevention research (Philadelphia, Pa.)","url":"https://pubmed.ncbi.nlm.nih.gov/24654229","citation_count":15,"is_preprint":false},{"pmid":"32843486","id":"PMC_32843486","title":"A novel homozygous variant in TRAPPC2L results in a neurodevelopmental disorder and disrupts TRAPP complex function.","date":"2020","source":"Journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/32843486","citation_count":14,"is_preprint":false},{"pmid":"21180879","id":"PMC_21180879","title":"Transcriptional regulation of bidirectional gene pairs by 17-β-estradiol in MCF-7 breast cancer cells.","date":"2010","source":"Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas","url":"https://pubmed.ncbi.nlm.nih.gov/21180879","citation_count":9,"is_preprint":false},{"pmid":"39273027","id":"PMC_39273027","title":"A Humanized Yeast Model for Studying TRAPP Complex Mutations; Proof-of-Concept Using Variants from an Individual with a TRAPPC1-Associated Neurodevelopmental Syndrome.","date":"2024","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/39273027","citation_count":4,"is_preprint":false},{"pmid":"29747491","id":"PMC_29747491","title":"Gastric Mucosal Atrophy Impedes Housekeeping Gene Methylation in Gastric Cancer Patients.","date":"2018","source":"Cancer research and treatment","url":"https://pubmed.ncbi.nlm.nih.gov/29747491","citation_count":3,"is_preprint":false},{"pmid":"36849228","id":"PMC_36849228","title":"TRAPPC2L-related disorder: first homozygous protein-truncating variant and further delineation of the phenotype.","date":"2023","source":"Journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/36849228","citation_count":2,"is_preprint":false},{"pmid":"40345286","id":"PMC_40345286","title":"Proteomic hub proteins CDKN2B, TRAPPC2L, WFS1, and ARPP19 drive biochemical recurrence and metastatic progression in prostate cancer: Protein macromolecule action.","date":"2025","source":"International journal of biological macromolecules","url":"https://pubmed.ncbi.nlm.nih.gov/40345286","citation_count":0,"is_preprint":false},{"pmid":"40539230","id":"PMC_40539230","title":"TRAPPC2l Participates in Male Germ Cell Development by Regulating Cell Division.","date":"2025","source":"Cell proliferation","url":"https://pubmed.ncbi.nlm.nih.gov/40539230","citation_count":0,"is_preprint":false},{"pmid":"39985057","id":"PMC_39985057","title":"KBG syndrome: report and follow-up on three unrelated patients observed at different ages.","date":"2025","source":"Italian journal of pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/39985057","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.08.04.605925","title":"A humanized yeast model for studying TRAPP complex mutations; proof-of-concept using variants from an individual with a  <i>TRAPPC1</i>  -associated neurodevelopmental syndrome","date":"2024-08-06","source":"bioRxiv","url":"https://doi.org/10.1101/2024.08.04.605925","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":11053,"output_tokens":1956,"usd":0.031249,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8972,"output_tokens":2849,"usd":0.058042,"stage2_stop_reason":"end_turn"},"total_usd":0.089291,"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\": 2009,\n      \"finding\": \"TRAPPC2L physically interacts with TRAPP complex components and co-fractionates with a portion of cellular TRAPP on very low-density membranes, distinct from the Golgi-associated TRAPP pool. RNAi-mediated knockdown of TRAPPC2L in HeLa cells causes Golgi fragmentation, implicating it in Golgi dynamics. Yeast complementation studies showed TRAPPC2L and TRAPPC2 are functionally distinct despite sequence relatedness.\",\n      \"method\": \"Gradient fractionation of cellular membranes, RNA interference knockdown with Golgi morphology readout, yeast complementation assays\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (fractionation, RNAi phenotype, yeast complementation) in a single lab study\",\n      \"pmids\": [\"19416478\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"A missense variant p.Asp37Tyr in TRAPPC2L abolishes the interaction between TRAPPC2L and TRAPPC10/Trs130 (a TRAPP II component), as shown by yeast two-hybrid analysis. Patient fibroblasts showed specific membrane trafficking delays and elevated levels of active RAB11, linking TRAPPC2L to TRAPP II-mediated RAB11 GEF activity.\",\n      \"method\": \"Yeast two-hybrid analysis, membrane trafficking assays in patient fibroblasts, RAB11 activation assays\",\n      \"journal\": \"Journal of medical genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal interaction mapping by Y2H and cell biological trafficking assays, single lab with two orthogonal methods\",\n      \"pmids\": [\"30120216\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"A second missense variant p.Ala2Gly in TRAPPC2L disrupts its interaction with TRAPPC6a (another core TRAPP protein), as demonstrated by yeast two-hybrid assay and in vitro binding, while the p.Asp37Tyr variant does not affect this interaction. Size exclusion chromatography indicated the p.Ala2Gly variant affects overall TRAPP complex assembly. Both variants increased active RAB11 levels in patient fibroblasts and caused membrane trafficking delays into and out of the Golgi, positioning TRAPPC2L as a putative adaptor for other TRAPP subunits.\",\n      \"method\": \"Yeast two-hybrid assay, in vitro binding assay, size exclusion chromatography, membrane trafficking assays in patient fibroblasts, RAB11 activation assays\",\n      \"journal\": \"Journal of medical genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro binding and Y2H for interaction, SEC for complex assembly, cell biological assays for trafficking, multiple orthogonal methods in one study\",\n      \"pmids\": [\"32843486\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In Aspergillus nidulans, the TRAPPC2L ortholog Tca17 binds to the 'Trs33 side' of the TRAPP core and recruits TRAPPC11, TRAPPC12, and TRAPPC13 subunits to form TRAPPIII. Additionally, Tca17 participates in a stable TRAPPII-specific subcomplex with Trs120/Trs130/Trs65, and its incorporation into core TRAPP (via Trs20 and Trs33) generates TRAPPII. This positions TRAPPC2L as a structural scaffold/adaptor in both TRAPPII and TRAPPIII assembly.\",\n      \"method\": \"Size-fractionation chromatography, single-step purification coupled to mass spectrometry, negative-stain electron microscopy, genetic epistasis using constitutively active RAB alleles\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — biochemical purification with MS, EM structural analysis, and genetic epistasis in multiple orthogonal experiments\",\n      \"pmids\": [\"31869332\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Mutant TRAPPC10 variants weaken the interaction between TRAPPC10 and its putative adaptor protein TRAPPC2L, as demonstrated by molecular interaction studies. This establishes TRAPPC2L as an adaptor bridging TRAPPC10 into the TRAPP II complex.\",\n      \"method\": \"Molecular interaction/binding studies between mutant TRAPPC10 and TRAPPC2L\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — interaction studies described in abstract without full methodological detail, single lab\",\n      \"pmids\": [\"35298461\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Human TRAPPC2L can functionally replace its yeast ortholog (Tca17) in Saccharomyces cerevisiae, demonstrating sufficient conservation of function for humanized yeast complementation. This confirms TRAPPC2L as a genuine ortholog of yeast Tca17 with conserved TRAPP-related function.\",\n      \"method\": \"Humanized yeast complementation using CRISPR/Cas9 scar-less editing to replace yeast subunit with human TRAPPC2L\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct genetic complementation in yeast, single study with clean functional readout\",\n      \"pmids\": [\"39273027\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Knockout of Trappc2l in male mice causes complete male infertility without developmental abnormalities in other tissues. Histological examination revealed formation of germ cell syncytial structures with multiple nuclei starting at embryonic day E17.5, with complete germ cell loss by 2 weeks postnatally. The syncytia arise from abnormal cell division (not cell fusion), and meiosis-associated genes Stra8 and Sycp3 are aberrantly expressed in embryonic Trappc2l-deficient germ cells, indicating TRAPPC2L is required for maintaining mitotic quiescence in male germ cells.\",\n      \"method\": \"Trappc2l knockout mouse model, histological examination, marker gene expression analysis (Stra8, Sycp3), cell division vs. fusion discrimination assays\",\n      \"journal\": \"Cell proliferation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO mouse model with specific cellular phenotype and mechanistic follow-up, single lab\",\n      \"pmids\": [\"40539230\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TRAPPC2L is a core subunit of the TRAPP complex that functions as a structural adaptor: it interacts with TRAPPC6a and TRAPPC10 to scaffold TRAPP II assembly, and its ortholog Tca17 in fungi recruits TRAPPC11/12/13 into TRAPPIII; loss-of-function or disease-associated missense variants disrupt these interactions, impair membrane trafficking through the Golgi, and elevate active RAB11 levels, while in vivo knockout in mice additionally reveals an essential role in maintaining mitotic quiescence of male germ cells.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TRAPPC2L is a core subunit of the multimeric TRAPP complex that acts as a structural adaptor coordinating TRAPP assembly and Golgi-associated membrane trafficking [#0, #2]. It physically interacts with TRAPP components and partitions in part to a low-density membrane pool distinct from the Golgi-associated TRAPP, and its depletion fragments the Golgi, establishing a role in Golgi dynamics [#0]. Mechanistically, TRAPPC2L bridges specific TRAPP subunits into higher-order complexes: it binds TRAPPC6a and TRAPPC10/Trs130 to support TRAPP II assembly [#1, #2, #4], and the conserved yeast/fungal ortholog Tca17 docks on the Trs33 side of the TRAPP core to recruit TRAPPC11/12/13 into TRAPPIII and to generate the TRAPPII-specific subcomplex, marking TRAPPC2L as a scaffold for both TRAPPII and TRAPPIII [#3]; human TRAPPC2L functionally substitutes for yeast Tca17, confirming conserved function [#5]. Disease-associated missense variants act through this adaptor function: p.Asp37Tyr abolishes TRAPPC2L–TRAPPC10 binding while p.Ala2Gly disrupts TRAPPC2L–TRAPPC6a binding and perturbs overall complex assembly, and both delay trafficking into and out of the Golgi and elevate levels of active RAB11 in patient fibroblasts, linking TRAPPC2L to TRAPP II–dependent RAB11 GEF activity [#1, #2]. Beyond trafficking, knockout of Trappc2l in mice causes male infertility through formation of multinucleate germ cell syncytia arising from abnormal cell division and aberrant expression of meiotic genes Stra8 and Sycp3, identifying an essential role in maintaining mitotic quiescence of male germ cells [#6].\",\n  \"teleology\": [\n    {\n      \"year\": 2009,\n      \"claim\": \"Established that TRAPPC2L is a bona fide TRAPP-associated protein with a distinct membrane pool and a functional requirement in Golgi maintenance, separating it from its sequence relative TRAPPC2.\",\n      \"evidence\": \"Membrane gradient fractionation, RNAi knockdown with Golgi morphology readout, and yeast complementation in HeLa cells\",\n      \"pmids\": [\"19416478\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specific TRAPP subunit contacts not mapped\", \"Molecular basis of the low-density membrane pool unknown\", \"No link to a downstream GTPase yet\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Connected TRAPPC2L to TRAPP II function and RAB11 regulation by showing a disease missense variant abolishes binding to TRAPPC10 and elevates active RAB11.\",\n      \"evidence\": \"Yeast two-hybrid interaction mapping, trafficking assays and RAB11 activation assays in patient fibroblasts\",\n      \"pmids\": [\"30120216\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether TRAPPC2L directly modulates GEF activity vs. complex integrity unresolved\", \"Single variant tested\", \"Structural basis of the TRAPPC10 contact not defined\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Defined TRAPPC2L's ortholog Tca17 as a structural scaffold positioned on the Trs33 side of the TRAPP core that drives both TRAPPIII and TRAPPII assembly, providing the mechanistic basis for its adaptor role.\",\n      \"evidence\": \"Size-fractionation chromatography, single-step purification with mass spectrometry, negative-stain EM, and genetic epistasis with constitutively active RAB alleles in Aspergillus nidulans\",\n      \"pmids\": [\"31869332\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct extrapolation of fungal architecture to human complexes not demonstrated\", \"High-resolution structure of the human complex absent\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Distinguished two adaptor contacts by showing p.Ala2Gly disrupts TRAPPC6a binding and overall complex assembly whereas p.Asp37Tyr does not, refining TRAPPC2L as a multi-interface adaptor in TRAPP assembly.\",\n      \"evidence\": \"Yeast two-hybrid and in vitro binding assays, size exclusion chromatography, and trafficking/RAB11 assays in patient fibroblasts\",\n      \"pmids\": [\"32843486\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative contribution of each contact to GEF output not measured\", \"Tissue-level consequences of assembly defects unclear\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Reinforced the TRAPPC2L–TRAPPC10 bridging model by showing mutant TRAPPC10 weakens the interaction, framing TRAPPC2L as the adaptor incorporating TRAPPC10 into TRAPP II.\",\n      \"evidence\": \"Molecular interaction/binding studies between mutant TRAPPC10 and TRAPPC2L\",\n      \"pmids\": [\"35298461\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Methodological detail limited\", \"Reciprocal validation and stoichiometry not reported\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Confirmed functional conservation by demonstrating human TRAPPC2L can replace yeast Tca17, validating cross-species mechanistic inferences.\",\n      \"evidence\": \"Humanized yeast complementation via CRISPR/Cas9 scar-less subunit replacement\",\n      \"pmids\": [\"39273027\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Complementation does not resolve which human-specific contacts are essential\", \"Quantitative fitness of humanized strain not detailed\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Revealed an in vivo role beyond trafficking, showing TRAPPC2L is required to maintain mitotic quiescence of male germ cells, with loss causing syncytia and infertility.\",\n      \"evidence\": \"Trappc2l knockout mouse, histology, Stra8/Sycp3 marker expression, and cell division vs. fusion discrimination\",\n      \"pmids\": [\"40539230\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanistic link between TRAPP trafficking function and germ cell quiescence unknown\", \"Whether the phenotype is RAB11-dependent untested\", \"Role in female germline not addressed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How TRAPPC2L's adaptor/assembly role mechanistically connects to RAB11 GEF activity and to germ cell mitotic quiescence remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structure of the human TRAPP complex with TRAPPC2L\", \"Causal pathway from trafficking defect to germ cell division phenotype unmapped\", \"Direct demonstration of GEF modulation by TRAPPC2L lacking\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 2, 3, 4]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [0, 2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [0, 1, 2]}\n    ],\n    \"complexes\": [\"TRAPP II\", \"TRAPP III\"],\n    \"partners\": [\"TRAPPC10\", \"TRAPPC6a\", \"TRAPPC11\", \"TRAPPC12\", \"TRAPPC13\", \"RAB11\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}