{"gene":"TRAPPC1","run_date":"2026-06-10T10:51:55","timeline":{"discoveries":[{"year":2000,"finding":"The TRAPP complex (containing Bet5p/TRAPPC1 ortholog) preferentially binds the nucleotide-free form of Ypt1p and stimulates guanine nucleotide exchange (GEF activity) on Ypt1p; temperature-sensitive mutations in Bet5p impair GDP displacement from Ypt1p, and purified TRAPP complex accelerates nucleotide exchange on Ypt1p in vitro.","method":"Biochemical nucleotide exchange assay with purified TRAPP complex; analysis of temperature-sensitive Bet5p mutants; in vitro binding to nucleotide-free Ypt1p","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with purified complex, mutagenesis of subunits including Bet5p, replicated with multiple mutant alleles","pmids":["11038176"],"is_preprint":false},{"year":1998,"finding":"Yeast Bet5p (TRAPPC1 ortholog) forms a complex with Bet3p and is required for ER-to-Golgi vesicular transport; temperature-sensitive bet5-1 mutants block transport of carboxypeptidase Y and alpha-factor, consistent with a block between the ER and Golgi apparatus. High-copy suppressors of bet5-1 include ER-to-Golgi transport genes (BET1, SEC22, USO1, DSS4), placing Bet5p in this pathway.","method":"Genetic complementation, temperature-sensitive mutant analysis (bet5-1), high-copy suppressor screen, carboxypeptidase Y and alpha-factor transport assays","journal":"Genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with multiple suppressors, two orthogonal transport assays, replicated in yeast model","pmids":["9611195"],"is_preprint":false},{"year":1999,"finding":"Human MUM-2 (TRAPPC1/BET5 homolog) functionally complements a yeast bet5 deletion mutant, demonstrating conservation of function across eukaryotes; a point mutation in MUM-2 found in melanoma cells does not destroy this complementation activity.","method":"Yeast complementation assay (bet5 deletion rescued by human MUM-2/TRAPPC1 wild-type and mutant alleles)","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct complementation experiment in yeast; single lab, single method but clean genetic readout","pmids":["10582700"],"is_preprint":false},{"year":2014,"finding":"The yeast TRAPP-associated protein Tca17 adopts the longin fold characteristic of the Bet5 (TRAPPC1) family of TRAPP subunits and shares a binding motif for interaction with other TRAPP complex members, suggesting Bet5/TRAPPC1 uses this longin fold as an interface for complex assembly.","method":"X-ray crystallography of Tca17 at 1.8 Å resolution; structural comparison with Bet5/TRAPPC1 family","journal":"The FEBS journal","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — crystal structure with functional inference about binding motif, but mechanistic follow-up on TRAPPC1 itself is indirect (structural comparison)","pmids":["24961828"],"is_preprint":false},{"year":2022,"finding":"Trappc1 deficiency in thymic epithelial cells (TECs) disrupts ER-to-Golgi protein transport, causing ER stress, activation of unfolded protein response (UPR) and Atf4-CHOP-mediated apoptosis, as well as ROS-mediated ferroptosis, leading to thymus atrophy and blocked TEC maturation.","method":"TEC-specific conditional Trappc1 knockout mice; RNA-seq; molecular assays for UPR, apoptosis markers, ROS/ferroptosis markers; ER and Golgi morphology assessment","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional KO with defined cellular phenotype, multiple orthogonal molecular readouts, single lab","pmids":["35908180"],"is_preprint":false},{"year":2024,"finding":"Trappc1 deficiency in naive T cells reduces ER-to-Golgi protein transport, enhances unfolded protein response, increases p53 transcription and lipid peroxide accumulation, and induces ferroptosis, leading to decreased peripheral naive T cell survival and spontaneous autoinflammatory disease.","method":"CD4cre-Trappc1flox/flox conditional KO mice; adoptive transfer assays; RNA-seq; measurement of ER stress markers, Ca2+, oxidative phosphorylation, lipid peroxides; lipid peroxidation inhibitor rescue","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional KO with adoptive transfer, multiple orthogonal assays, pharmacological rescue, single lab","pmids":["38234007"],"is_preprint":false},{"year":2022,"finding":"TRAPPC1 deficiency in common myeloid progenitors (CMPs) causes ER stress and apoptosis via a Ca2+-mitochondria-dependent pathway, and cell cycle arrest/senescence via PERK activation and upregulation of p21, impairing CMP differentiation into monocytes and neutrophils.","method":"Inducible ER-TRAPPC1 knockout mice; bone marrow chimeric mouse models; in vivo and in vitro differentiation assays; molecular assays for ER stress, Ca2+ flux, mitochondrial function, PERK pathway, p21","journal":"EMBO reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — inducible KO with chimeric rescue model, multiple pathway assays, single lab","pmids":["36440617"],"is_preprint":false},{"year":2024,"finding":"The TRAPPC1 paternal variant p.(His22_Lys24del) is conditional-lethal in humanized yeast and impairs secretion and non-selective autophagy, while the maternal variant p.(Val121Alafs*3) is non-functional; fibroblasts from the affected individual show membrane trafficking defects and altered Golgi morphology rescued by wild-type TRAPPC1.","method":"Humanized yeast model (CRISPR/Cas9 replacement of yeast BET5 with human TRAPPC1 variants); secretion assays; autophagy assays; patient fibroblast trafficking and Golgi morphology assays; complementation rescue with WT TRAPPC1","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — complementation in humanized yeast plus patient fibroblast rescue, two orthogonal systems, single lab","pmids":["39273027"],"is_preprint":false}],"current_model":"TRAPPC1 (BET5/Bet5p) is an essential core subunit of the TRAPP complex that mediates ER-to-Golgi vesicular transport by contributing to the complex's guanine nucleotide exchange factor (GEF) activity toward Rab1/Ypt1p; it uses a longin fold to participate in TRAPP complex assembly, and its loss disrupts ER-to-Golgi protein trafficking, induces ER stress and unfolded protein response, and leads to apoptosis and/or ferroptosis in multiple cell types including thymic epithelial cells, naive T cells, and myeloid progenitors."},"narrative":{"mechanistic_narrative":"TRAPPC1 (BET5/Bet5p) is an essential core subunit of the multisubunit TRAPP complex that drives ER-to-Golgi vesicular transport [PMID:9611195]. As part of the assembled complex, it contributes to guanine nucleotide exchange factor (GEF) activity toward the Rab GTPase Ypt1p/Rab1: the TRAPP complex preferentially binds the nucleotide-free form of Ypt1p and accelerates GDP/GTP exchange, and temperature-sensitive Bet5p mutations impair GDP displacement [PMID:11038176]. TRAPPC1 partners with Bet3p within the complex, and its function is genetically embedded in the ER-to-Golgi pathway alongside BET1, SEC22, USO1 and DSS4 [PMID:9611195]; the human ortholog (MUM-2) functionally complements yeast bet5 loss, establishing cross-eukaryotic conservation of this role [PMID:10582700]. Loss of TRAPPC1 disrupts ER-to-Golgi protein trafficking and alters Golgi morphology, triggering ER stress and the unfolded protein response that converge on cell death and impaired differentiation across multiple lineages — Atf4-CHOP apoptosis and ROS-driven ferroptosis in thymic epithelial cells [PMID:35908180], p53/lipid-peroxide-dependent ferroptosis in naive T cells [PMID:38234007], and Ca2+-mitochondria apoptosis plus PERK/p21 senescence in myeloid progenitors [PMID:36440617]. Biallelic TRAPPC1 variants in an affected individual cause membrane trafficking and Golgi defects in patient fibroblasts that are rescued by wild-type TRAPPC1, linking the gene to a human disorder of secretion and autophagy [PMID:39273027].","teleology":[{"year":1998,"claim":"Established that Bet5p/TRAPPC1 is required for ER-to-Golgi transport and acts within a defined secretory pathway, answering where in the secretory route this subunit functions.","evidence":"Temperature-sensitive bet5-1 mutant analysis, high-copy suppressor screen, and carboxypeptidase Y/alpha-factor transport assays in yeast","pmids":["9611195"],"confidence":"High","gaps":["Did not define the biochemical activity of the complex","Did not identify the GTPase target","Subunit composition and stoichiometry not resolved"]},{"year":1999,"claim":"Demonstrated that the human ortholog can substitute for yeast Bet5p, establishing functional conservation of TRAPPC1 across eukaryotes.","evidence":"Yeast bet5 deletion complementation by wild-type and mutant human MUM-2/TRAPPC1 alleles","pmids":["10582700"],"confidence":"Medium","gaps":["Single lab, single complementation readout","No biochemical characterization of the human protein","Melanoma-associated point mutation had no functional effect, leaving its relevance unclear"]},{"year":2000,"claim":"Identified the molecular activity of the TRAPP complex — GEF activity toward Ypt1p — and showed Bet5p is functionally required, answering how the complex acts on Rab signaling.","evidence":"In vitro nucleotide exchange assays with purified TRAPP complex, binding to nucleotide-free Ypt1p, and temperature-sensitive Bet5p mutant analysis","pmids":["11038176"],"confidence":"High","gaps":["Did not isolate the catalytic contribution of TRAPPC1 alone","Structural basis of nucleotide exchange not resolved","Mammalian Rab1 GEF activity not directly tested"]},{"year":2014,"claim":"Provided structural insight that the Bet5/TRAPPC1 family adopts a longin fold serving as an interaction interface, addressing how the subunit assembles into the complex.","evidence":"X-ray crystallography of the related Tca17 at 1.8 Å with structural comparison to the Bet5/TRAPPC1 family","pmids":["24961828"],"confidence":"Medium","gaps":["Inference is from a related subunit, not a TRAPPC1 structure","Specific TRAPPC1 contact residues not experimentally mapped","Role of the fold in GEF catalysis untested"]},{"year":2022,"claim":"Connected TRAPPC1 loss to defined cellular pathology, showing that disrupted ER-to-Golgi transport triggers ER stress/UPR and converging death pathways in tissue-specific contexts.","evidence":"Tissue-specific conditional Trappc1 knockout mice (thymic epithelial cells; inducible myeloid-progenitor KO with bone marrow chimeras), RNA-seq, and assays for UPR, apoptosis, ferroptosis, Ca2+/mitochondria, PERK and p21","pmids":["35908180","36440617"],"confidence":"Medium","gaps":["Single lab per study","Direct link from trafficking defect to specific death effector not fully dissected","Whether phenotypes reflect TRAPP GEF activity loss versus other functions unresolved"]},{"year":2024,"claim":"Extended the loss-of-function consequences to peripheral T cell survival and to a human disorder, showing trafficking failure drives ferroptosis/autoinflammation and that patient variants impair secretion and autophagy.","evidence":"CD4cre-Trappc1 conditional KO mice with adoptive transfer and lipid-peroxidation rescue; humanized yeast modeling of patient variants plus patient fibroblast trafficking/Golgi rescue with wild-type TRAPPC1","pmids":["38234007","39273027"],"confidence":"Medium","gaps":["Disease characterization based on a single affected individual","Mechanistic link between trafficking defect and p53/lipid-peroxide axis incompletely defined","Autophagy contribution versus secretory defect not separated"]},{"year":null,"claim":"How TRAPPC1's longin fold contributes catalytically to Rab1 nucleotide exchange in the mammalian complex, and which downstream effector links its loss to lineage-specific apoptosis versus ferroptosis, remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of the human TRAPPC1 within the assembled GEF","No direct measurement of TRAPPC1's individual contribution to mammalian Rab1 exchange","Effector selecting apoptosis versus ferroptosis across cell types unidentified"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[0]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[1,4]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[1,7]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[1,0]},{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[4,6]}],"complexes":["TRAPP complex"],"partners":["BET3","YPT1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9Y5R8","full_name":"Trafficking protein particle complex subunit 1","aliases":["BET5 homolog","Multiple myeloma protein 2","MUM-2"],"length_aa":145,"mass_kda":16.8,"function":"May play a role in vesicular transport from endoplasmic reticulum to Golgi","subcellular_location":"Golgi apparatus, cis-Golgi network; Endoplasmic reticulum","url":"https://www.uniprot.org/uniprotkb/Q9Y5R8/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/TRAPPC1","classification":"Common Essential","n_dependent_lines":1189,"n_total_lines":1208,"dependency_fraction":0.984271523178808},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000170043","cell_line_id":"CID000468","localizations":[{"compartment":"cytoplasmic","grade":3},{"compartment":"golgi","grade":3},{"compartment":"vesicles","grade":3},{"compartment":"nucleoplasm","grade":2}],"interactors":[{"gene":"YWHAB","stoichiometry":10.0},{"gene":"TRAPPC2B;TRAPPC2","stoichiometry":10.0},{"gene":"TRAPPC13","stoichiometry":10.0},{"gene":"TRAPPC2L","stoichiometry":10.0},{"gene":"TRAPPC3","stoichiometry":10.0},{"gene":"TRAPPC12;CGI-87","stoichiometry":10.0},{"gene":"TRAPPC8","stoichiometry":10.0},{"gene":"TRAPPC4","stoichiometry":10.0},{"gene":"TRAPPC5","stoichiometry":10.0},{"gene":"TRAPPC2","stoichiometry":10.0}],"url":"https://opencell.sf.czbiohub.org/target/CID000468","total_profiled":1310},"omim":[{"mim_id":"613776","title":"CHROMOSOME 17p13.1 DELETION SYNDROME","url":"https://www.omim.org/entry/613776"},{"mim_id":"610971","title":"TRAFFICKING PROTEIN PARTICLE COMPLEX, SUBUNIT 4; TRAPPC4","url":"https://www.omim.org/entry/610971"},{"mim_id":"610969","title":"TRAFFICKING PROTEIN PARTICLE COMPLEX, SUBUNIT 1; TRAPPC1","url":"https://www.omim.org/entry/610969"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/TRAPPC1"},"hgnc":{"alias_symbol":["MUM2","BET5"],"prev_symbol":[]},"alphafold":{"accession":"Q9Y5R8","domains":[{"cath_id":"3.30.450.70","chopping":"2-135","consensus_level":"high","plddt":96.7428,"start":2,"end":135}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y5R8","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y5R8-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y5R8-F1-predicted_aligned_error_v6.png","plddt_mean":95.25},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TRAPPC1","jax_strain_url":"https://www.jax.org/strain/search?query=TRAPPC1"},"sequence":{"accession":"Q9Y5R8","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9Y5R8.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9Y5R8/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y5R8"}},"corpus_meta":[{"pmid":"11038176","id":"PMC_11038176","title":"TRAPP stimulates guanine nucleotide exchange on Ypt1p.","date":"2000","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/11038176","citation_count":166,"is_preprint":false},{"pmid":"10582700","id":"PMC_10582700","title":"Two antigens recognized by autologous cytolytic T lymphocytes on a melanoma result from a single point mutation in an essential housekeeping gene.","date":"1999","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/10582700","citation_count":59,"is_preprint":false},{"pmid":"9611195","id":"PMC_9611195","title":"A high copy suppressor screen reveals genetic interactions between BET3 and a new gene. Evidence for a novel complex in ER-to-Golgi transport.","date":"1998","source":"Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/9611195","citation_count":27,"is_preprint":false},{"pmid":"35908180","id":"PMC_35908180","title":"Trappc1 deficiency impairs thymic epithelial cell development by breaking endoplasmic reticulum homeostasis.","date":"2022","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/35908180","citation_count":9,"is_preprint":false},{"pmid":"38234007","id":"PMC_38234007","title":"Trappc1 intrinsically prevents ferroptosis of naive T cells to avoid spontaneous autoinflammatory disease in mice.","date":"2024","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/38234007","citation_count":9,"is_preprint":false},{"pmid":"24961828","id":"PMC_24961828","title":"Crystal structure of the yeast TRAPP-associated protein Tca17.","date":"2014","source":"The FEBS journal","url":"https://pubmed.ncbi.nlm.nih.gov/24961828","citation_count":9,"is_preprint":false},{"pmid":"36440617","id":"PMC_36440617","title":"TRAPPC1 is essential for the maintenance and differentiation of common myeloid progenitors in mice.","date":"2022","source":"EMBO reports","url":"https://pubmed.ncbi.nlm.nih.gov/36440617","citation_count":6,"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":"41216601","id":"PMC_41216601","title":"Shared Biomarkers and Potential Mechanisms Between Hashimoto's Thyroiditis and Recurrent Miscarriage Revealed by Transcriptomics Analysis.","date":"2025","source":"International journal of general medicine","url":"https://pubmed.ncbi.nlm.nih.gov/41216601","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":7464,"output_tokens":2135,"usd":0.027209,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9181,"output_tokens":2824,"usd":0.058252,"stage2_stop_reason":"end_turn"},"total_usd":0.085461,"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\": 2000,\n      \"finding\": \"The TRAPP complex (containing Bet5p/TRAPPC1 ortholog) preferentially binds the nucleotide-free form of Ypt1p and stimulates guanine nucleotide exchange (GEF activity) on Ypt1p; temperature-sensitive mutations in Bet5p impair GDP displacement from Ypt1p, and purified TRAPP complex accelerates nucleotide exchange on Ypt1p in vitro.\",\n      \"method\": \"Biochemical nucleotide exchange assay with purified TRAPP complex; analysis of temperature-sensitive Bet5p mutants; in vitro binding to nucleotide-free Ypt1p\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with purified complex, mutagenesis of subunits including Bet5p, replicated with multiple mutant alleles\",\n      \"pmids\": [\"11038176\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Yeast Bet5p (TRAPPC1 ortholog) forms a complex with Bet3p and is required for ER-to-Golgi vesicular transport; temperature-sensitive bet5-1 mutants block transport of carboxypeptidase Y and alpha-factor, consistent with a block between the ER and Golgi apparatus. High-copy suppressors of bet5-1 include ER-to-Golgi transport genes (BET1, SEC22, USO1, DSS4), placing Bet5p in this pathway.\",\n      \"method\": \"Genetic complementation, temperature-sensitive mutant analysis (bet5-1), high-copy suppressor screen, carboxypeptidase Y and alpha-factor transport assays\",\n      \"journal\": \"Genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with multiple suppressors, two orthogonal transport assays, replicated in yeast model\",\n      \"pmids\": [\"9611195\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Human MUM-2 (TRAPPC1/BET5 homolog) functionally complements a yeast bet5 deletion mutant, demonstrating conservation of function across eukaryotes; a point mutation in MUM-2 found in melanoma cells does not destroy this complementation activity.\",\n      \"method\": \"Yeast complementation assay (bet5 deletion rescued by human MUM-2/TRAPPC1 wild-type and mutant alleles)\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct complementation experiment in yeast; single lab, single method but clean genetic readout\",\n      \"pmids\": [\"10582700\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"The yeast TRAPP-associated protein Tca17 adopts the longin fold characteristic of the Bet5 (TRAPPC1) family of TRAPP subunits and shares a binding motif for interaction with other TRAPP complex members, suggesting Bet5/TRAPPC1 uses this longin fold as an interface for complex assembly.\",\n      \"method\": \"X-ray crystallography of Tca17 at 1.8 Å resolution; structural comparison with Bet5/TRAPPC1 family\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — crystal structure with functional inference about binding motif, but mechanistic follow-up on TRAPPC1 itself is indirect (structural comparison)\",\n      \"pmids\": [\"24961828\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Trappc1 deficiency in thymic epithelial cells (TECs) disrupts ER-to-Golgi protein transport, causing ER stress, activation of unfolded protein response (UPR) and Atf4-CHOP-mediated apoptosis, as well as ROS-mediated ferroptosis, leading to thymus atrophy and blocked TEC maturation.\",\n      \"method\": \"TEC-specific conditional Trappc1 knockout mice; RNA-seq; molecular assays for UPR, apoptosis markers, ROS/ferroptosis markers; ER and Golgi morphology assessment\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional KO with defined cellular phenotype, multiple orthogonal molecular readouts, single lab\",\n      \"pmids\": [\"35908180\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Trappc1 deficiency in naive T cells reduces ER-to-Golgi protein transport, enhances unfolded protein response, increases p53 transcription and lipid peroxide accumulation, and induces ferroptosis, leading to decreased peripheral naive T cell survival and spontaneous autoinflammatory disease.\",\n      \"method\": \"CD4cre-Trappc1flox/flox conditional KO mice; adoptive transfer assays; RNA-seq; measurement of ER stress markers, Ca2+, oxidative phosphorylation, lipid peroxides; lipid peroxidation inhibitor rescue\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional KO with adoptive transfer, multiple orthogonal assays, pharmacological rescue, single lab\",\n      \"pmids\": [\"38234007\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TRAPPC1 deficiency in common myeloid progenitors (CMPs) causes ER stress and apoptosis via a Ca2+-mitochondria-dependent pathway, and cell cycle arrest/senescence via PERK activation and upregulation of p21, impairing CMP differentiation into monocytes and neutrophils.\",\n      \"method\": \"Inducible ER-TRAPPC1 knockout mice; bone marrow chimeric mouse models; in vivo and in vitro differentiation assays; molecular assays for ER stress, Ca2+ flux, mitochondrial function, PERK pathway, p21\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — inducible KO with chimeric rescue model, multiple pathway assays, single lab\",\n      \"pmids\": [\"36440617\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"The TRAPPC1 paternal variant p.(His22_Lys24del) is conditional-lethal in humanized yeast and impairs secretion and non-selective autophagy, while the maternal variant p.(Val121Alafs*3) is non-functional; fibroblasts from the affected individual show membrane trafficking defects and altered Golgi morphology rescued by wild-type TRAPPC1.\",\n      \"method\": \"Humanized yeast model (CRISPR/Cas9 replacement of yeast BET5 with human TRAPPC1 variants); secretion assays; autophagy assays; patient fibroblast trafficking and Golgi morphology assays; complementation rescue with WT TRAPPC1\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — complementation in humanized yeast plus patient fibroblast rescue, two orthogonal systems, single lab\",\n      \"pmids\": [\"39273027\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TRAPPC1 (BET5/Bet5p) is an essential core subunit of the TRAPP complex that mediates ER-to-Golgi vesicular transport by contributing to the complex's guanine nucleotide exchange factor (GEF) activity toward Rab1/Ypt1p; it uses a longin fold to participate in TRAPP complex assembly, and its loss disrupts ER-to-Golgi protein trafficking, induces ER stress and unfolded protein response, and leads to apoptosis and/or ferroptosis in multiple cell types including thymic epithelial cells, naive T cells, and myeloid progenitors.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TRAPPC1 (BET5/Bet5p) is an essential core subunit of the multisubunit TRAPP complex that drives ER-to-Golgi vesicular transport [#1]. As part of the assembled complex, it contributes to guanine nucleotide exchange factor (GEF) activity toward the Rab GTPase Ypt1p/Rab1: the TRAPP complex preferentially binds the nucleotide-free form of Ypt1p and accelerates GDP/GTP exchange, and temperature-sensitive Bet5p mutations impair GDP displacement [#0]. TRAPPC1 partners with Bet3p within the complex, and its function is genetically embedded in the ER-to-Golgi pathway alongside BET1, SEC22, USO1 and DSS4 [#1]; the human ortholog (MUM-2) functionally complements yeast bet5 loss, establishing cross-eukaryotic conservation of this role [#2]. Loss of TRAPPC1 disrupts ER-to-Golgi protein trafficking and alters Golgi morphology, triggering ER stress and the unfolded protein response that converge on cell death and impaired differentiation across multiple lineages \\u2014 Atf4-CHOP apoptosis and ROS-driven ferroptosis in thymic epithelial cells [#4], p53/lipid-peroxide-dependent ferroptosis in naive T cells [#5], and Ca2+-mitochondria apoptosis plus PERK/p21 senescence in myeloid progenitors [#6]. Biallelic TRAPPC1 variants in an affected individual cause membrane trafficking and Golgi defects in patient fibroblasts that are rescued by wild-type TRAPPC1, linking the gene to a human disorder of secretion and autophagy [#7].\"\n  ,\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Established that Bet5p/TRAPPC1 is required for ER-to-Golgi transport and acts within a defined secretory pathway, answering where in the secretory route this subunit functions.\",\n      \"evidence\": \"Temperature-sensitive bet5-1 mutant analysis, high-copy suppressor screen, and carboxypeptidase Y/alpha-factor transport assays in yeast\",\n      \"pmids\": [\"9611195\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Did not define the biochemical activity of the complex\",\n        \"Did not identify the GTPase target\",\n        \"Subunit composition and stoichiometry not resolved\"\n      ]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Demonstrated that the human ortholog can substitute for yeast Bet5p, establishing functional conservation of TRAPPC1 across eukaryotes.\",\n      \"evidence\": \"Yeast bet5 deletion complementation by wild-type and mutant human MUM-2/TRAPPC1 alleles\",\n      \"pmids\": [\"10582700\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single lab, single complementation readout\",\n        \"No biochemical characterization of the human protein\",\n        \"Melanoma-associated point mutation had no functional effect, leaving its relevance unclear\"\n      ]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Identified the molecular activity of the TRAPP complex \\u2014 GEF activity toward Ypt1p \\u2014 and showed Bet5p is functionally required, answering how the complex acts on Rab signaling.\",\n      \"evidence\": \"In vitro nucleotide exchange assays with purified TRAPP complex, binding to nucleotide-free Ypt1p, and temperature-sensitive Bet5p mutant analysis\",\n      \"pmids\": [\"11038176\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Did not isolate the catalytic contribution of TRAPPC1 alone\",\n        \"Structural basis of nucleotide exchange not resolved\",\n        \"Mammalian Rab1 GEF activity not directly tested\"\n      ]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Provided structural insight that the Bet5/TRAPPC1 family adopts a longin fold serving as an interaction interface, addressing how the subunit assembles into the complex.\",\n      \"evidence\": \"X-ray crystallography of the related Tca17 at 1.8 \\u00c5 with structural comparison to the Bet5/TRAPPC1 family\",\n      \"pmids\": [\"24961828\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Inference is from a related subunit, not a TRAPPC1 structure\",\n        \"Specific TRAPPC1 contact residues not experimentally mapped\",\n        \"Role of the fold in GEF catalysis untested\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Connected TRAPPC1 loss to defined cellular pathology, showing that disrupted ER-to-Golgi transport triggers ER stress/UPR and converging death pathways in tissue-specific contexts.\",\n      \"evidence\": \"Tissue-specific conditional Trappc1 knockout mice (thymic epithelial cells; inducible myeloid-progenitor KO with bone marrow chimeras), RNA-seq, and assays for UPR, apoptosis, ferroptosis, Ca2+/mitochondria, PERK and p21\",\n      \"pmids\": [\"35908180\", \"36440617\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single lab per study\",\n        \"Direct link from trafficking defect to specific death effector not fully dissected\",\n        \"Whether phenotypes reflect TRAPP GEF activity loss versus other functions unresolved\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Extended the loss-of-function consequences to peripheral T cell survival and to a human disorder, showing trafficking failure drives ferroptosis/autoinflammation and that patient variants impair secretion and autophagy.\",\n      \"evidence\": \"CD4cre-Trappc1 conditional KO mice with adoptive transfer and lipid-peroxidation rescue; humanized yeast modeling of patient variants plus patient fibroblast trafficking/Golgi rescue with wild-type TRAPPC1\",\n      \"pmids\": [\"38234007\", \"39273027\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Disease characterization based on a single affected individual\",\n        \"Mechanistic link between trafficking defect and p53/lipid-peroxide axis incompletely defined\",\n        \"Autophagy contribution versus secretory defect not separated\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How TRAPPC1's longin fold contributes catalytically to Rab1 nucleotide exchange in the mammalian complex, and which downstream effector links its loss to lineage-specific apoptosis versus ferroptosis, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No structure of the human TRAPPC1 within the assembled GEF\",\n        \"No direct measurement of TRAPPC1's individual contribution to mammalian Rab1 exchange\",\n        \"Effector selecting apoptosis versus ferroptosis across cell types unidentified\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [1, 4]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [1, 7]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [1, 0]},\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [4, 6]}\n    ],\n    \"complexes\": [\"TRAPP complex\"],\n    \"partners\": [\"BET3\", \"YPT1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}