id: O43617 gene_symbol: TRAPPC3 product_type: PROTEIN status: COMPLETE taxon: id: NCBITaxon:9606 label: Homo sapiens description: >- TRAPPC3 is the human Bet3 homolog and a core TRAPP-complex subunit. It contributes to complex-level RAB1 guanine-nucleotide exchange factor activity, TRAPP/TRAPPII/TRAPPIII complex architecture, and ER-to-Golgi vesicle-mediated transport. Autophagophore-recruitment effects are best understood through TRAPP complex membership and TRAPPIII/RAB1 context rather than independent TRAPPC3-specific autophagy activity. alternative_products: - name: '1' id: O43617-1 - name: '2' id: O43617-2 sequence_note: VSP_047015 existing_annotations: - term: id: GO:0005085 label: guanyl-nucleotide exchange factor activity evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: contributes_to review: summary: TRAPPC3 contributes to complex-level RAB1 guanine-nucleotide exchange factor activity as a TRAPP subunit. action: ACCEPT reason: Accept with the contributes_to qualifier. The TRAPPC complex, not isolated TRAPPC3, provides the GEF activity for RAB1/Ypt1-family GTPases. additional_reference_ids: - Reactome:R-HSA-5694409 - Reactome:R-HSA-8877475 - PMID:21525244 supported_by: - &id001 reference_id: Reactome:R-HSA-5694409 supporting_text: The TRAPPC complex acts as a guanine-nucleotide exchange factor for RAB1, activating it - &id002 reference_id: Reactome:R-HSA-8877475 supporting_text: RAB1 nucleotide exchange is stimulated in these pathways by the GEF activity of the multisubunit TRAPPC complexes II and III - &id014 reference_id: PMID:21525244 supporting_text: the complex acts as a guanine nucleotide exchange factor (GEF) for Ypt1p - term: id: GO:0005829 label: cytosol evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: is_active_in review: summary: TRAPPC3-containing TRAPP reactions occur on the cytosolic/cytoplasmic side of ER-Golgi trafficking membranes. action: ACCEPT reason: Accept as supported location for a peripheral trafficking-complex subunit. additional_reference_ids: - Reactome:R-HSA-5694409 - Reactome:R-HSA-5694439 - Reactome:R-HSA-8877475 supported_by: - &id003 reference_id: Reactome:R-HSA-5694439 supporting_text: TRAPPC is a multi-subunit tethering complex that facilitates ER-to-Golgi traffic - *id001 - *id002 - term: id: GO:0006888 label: endoplasmic reticulum to Golgi vesicle-mediated transport evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: involved_in review: summary: TRAPPC3-containing TRAPP complexes mediate ER-to-Golgi vesicle traffic through TRAPP/RAB1 biology. action: ACCEPT reason: Accept as a core process for TRAPPC3. Multiple human/mammalian TRAPP sources and Reactome support ER-to-Golgi trafficking. additional_reference_ids: - PMID:18930054 - PMID:21525244 - Reactome:R-HSA-5694439 - Reactome:R-HSA-8877475 supported_by: - &id004 reference_id: PMID:18930054 supporting_text: The transport protein particle (TRAPP) complex is required for proper vesicular transport from the ER to the Golgi - &id011 reference_id: PMID:21525244 supporting_text: C4orf41 and TTC-15 (which we call TRAPPC11 and TRAPPC12, respectively) in ER-to-Golgi trafficking at a very early stage - *id003 - *id001 - term: id: GO:0006891 label: intra-Golgi vesicle-mediated transport evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: involved_in review: summary: Intra-Golgi transport is plausible through TRAPPII/Golgi trafficking context but is less central than ER-to-Golgi transport for human TRAPPC3. action: KEEP_AS_NON_CORE reason: Keep as non-core. The TRAPPII/Golgi evidence supports a context-specific trafficking role, while the core TRAPPC3 process remains ER-to-Golgi/TRAPP/RAB1 transport. additional_reference_ids: - PMID:21453443 - PMID:18930054 supported_by: - &id006 reference_id: PMID:21453443 supporting_text: for distinct tethering events at Golgi membranes - &id007 reference_id: PMID:18930054 supporting_text: different functions in the regulation of ER-to-Golgi traffic - term: id: GO:0030008 label: TRAPP complex evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: part_of review: summary: TRAPPC3/Bet3 is a core TRAPP complex subunit. action: ACCEPT reason: Accept as core cellular-component membership. This is the cleanest gene-level representation of the PN TRAPP component leaf. additional_reference_ids: - PMID:16828797 - PMID:21525244 - PMID:27066478 supported_by: - &id008 reference_id: PMID:16828797 supporting_text: crystal structure of a human Bet3-Tpc6B heterodimer, which represents a core sub-complex in the assembly of TRAPP - &id009 reference_id: PMID:16828797 supporting_text: Bet3-Tpc6A and Bet3-Tpc6B, are able to recruit Mum2, a further TRAPP subunit - &id010 reference_id: PMID:21525244 supporting_text: the mammalian orthologues named TRAPPC1, TRAPPC2, TRAPPC3, TRAPPC4, TRAPPC5, and TRAPPC6a/b - term: id: GO:0033106 label: cis-Golgi network membrane evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: is_active_in review: summary: cis-Golgi network membrane is a supported active site for TRAPPC3-containing TRAPP complexes. action: ACCEPT reason: Accept as a supported active location for TRAPP/RAB1 ER-to-Golgi trafficking. additional_reference_ids: - Reactome:R-HSA-5694439 - PMID:18930054 supported_by: - *id004 - &id005 reference_id: Reactome:R-HSA-5694439 supporting_text: TRAPPC is a guanine-nucleotide exchange factor for RAB1 and is recruited to ER-derived vesicles by virtue of an interaction between the TRAPPC component TRAPPC3 and the coat protein SEC23 - term: id: GO:0005783 label: endoplasmic reticulum evidence_type: IEA original_reference_id: GO_REF:0000044 qualifier: located_in review: summary: TRAPPC3 participates in ER-derived vesicle trafficking and is mapped to the endoplasmic reticulum. action: ACCEPT reason: Accept as a supported location for ER-to-Golgi trafficking. additional_reference_ids: - PMID:18930054 - Reactome:R-HSA-5694439 supported_by: - *id004 - *id005 - term: id: GO:0005794 label: Golgi apparatus evidence_type: IEA original_reference_id: GO_REF:0000044 qualifier: located_in review: summary: TRAPPC3 functions in TRAPP trafficking at Golgi/cis-Golgi membranes. action: ACCEPT reason: Accept as supported location for TRAPP-mediated ER-to-Golgi and Golgi trafficking. additional_reference_ids: - PMID:18930054 - PMID:21453443 supported_by: - *id004 - *id006 - *id007 - term: id: GO:0030008 label: TRAPP complex evidence_type: IEA original_reference_id: GO_REF:0000120 qualifier: part_of review: summary: TRAPPC3/Bet3 is a core TRAPP complex subunit. action: ACCEPT reason: Accept as core cellular-component membership. This is the cleanest gene-level representation of the PN TRAPP component leaf. additional_reference_ids: - PMID:16828797 - PMID:21525244 - PMID:27066478 supported_by: - *id008 - *id009 - *id010 - term: id: GO:0048193 label: Golgi vesicle transport evidence_type: IEA original_reference_id: GO_REF:0000002 qualifier: involved_in review: summary: Golgi vesicle transport is a broad trafficking context supported by TRAPP/TRAPPII biology. action: KEEP_AS_NON_CORE reason: Keep as non-core because it is broader/less precise than ER-to-Golgi vesicle-mediated transport and intra-Golgi TRAPPII context. additional_reference_ids: - PMID:21453443 - PMID:18930054 supported_by: - *id006 - *id007 - term: id: GO:0005515 label: protein binding evidence_type: IPI original_reference_id: PMID:16189514 qualifier: enables review: summary: Generic protein binding is not informative for TRAPPC3. action: MARK_AS_OVER_ANNOTATED reason: Mark as over-annotated. Specific interaction biology should be represented as TRAPP/TRAPPII/TRAPPIII complex membership and TRAPP/RAB1 trafficking context, not generic GO:0005515. - term: id: GO:0005515 label: protein binding evidence_type: IPI original_reference_id: PMID:16828797 qualifier: enables review: summary: Generic protein binding is not informative for TRAPPC3. action: MARK_AS_OVER_ANNOTATED reason: Mark as over-annotated. Specific interaction biology should be represented as TRAPP/TRAPPII/TRAPPIII complex membership and TRAPP/RAB1 trafficking context, not generic GO:0005515. - term: id: GO:0005515 label: protein binding evidence_type: IPI original_reference_id: PMID:16908848 qualifier: enables review: summary: Generic protein binding is not informative for TRAPPC3. action: MARK_AS_OVER_ANNOTATED reason: Mark as over-annotated. Specific interaction biology should be represented as TRAPP/TRAPPII/TRAPPIII complex membership and TRAPP/RAB1 trafficking context, not generic GO:0005515. - term: id: GO:0005515 label: protein binding evidence_type: IPI original_reference_id: PMID:18930054 qualifier: enables review: summary: Generic protein binding is not informative for TRAPPC3. action: MARK_AS_OVER_ANNOTATED reason: Mark as over-annotated. Specific interaction biology should be represented as TRAPP/TRAPPII/TRAPPIII complex membership and TRAPP/RAB1 trafficking context, not generic GO:0005515. - term: id: GO:0005515 label: protein binding evidence_type: IPI original_reference_id: PMID:21453443 qualifier: enables review: summary: Generic protein binding is not informative for TRAPPC3. action: MARK_AS_OVER_ANNOTATED reason: Mark as over-annotated. Specific interaction biology should be represented as TRAPP/TRAPPII/TRAPPIII complex membership and TRAPP/RAB1 trafficking context, not generic GO:0005515. - term: id: GO:0005515 label: protein binding evidence_type: IPI original_reference_id: PMID:21827752 qualifier: enables review: summary: Generic protein binding is not informative for TRAPPC3. action: MARK_AS_OVER_ANNOTATED reason: Mark as over-annotated. Specific interaction biology should be represented as TRAPP/TRAPPII/TRAPPIII complex membership and TRAPP/RAB1 trafficking context, not generic GO:0005515. - term: id: GO:0005515 label: protein binding evidence_type: IPI original_reference_id: PMID:25416956 qualifier: enables review: summary: Generic protein binding is not informative for TRAPPC3. action: MARK_AS_OVER_ANNOTATED reason: Mark as over-annotated. Specific interaction biology should be represented as TRAPP/TRAPPII/TRAPPIII complex membership and TRAPP/RAB1 trafficking context, not generic GO:0005515. - term: id: GO:0005515 label: protein binding evidence_type: IPI original_reference_id: PMID:28514442 qualifier: enables review: summary: Generic protein binding is not informative for TRAPPC3. action: MARK_AS_OVER_ANNOTATED reason: Mark as over-annotated. Specific interaction biology should be represented as TRAPP/TRAPPII/TRAPPIII complex membership and TRAPP/RAB1 trafficking context, not generic GO:0005515. - term: id: GO:0005515 label: protein binding evidence_type: IPI original_reference_id: PMID:31515488 qualifier: enables review: summary: Generic protein binding is not informative for TRAPPC3. action: MARK_AS_OVER_ANNOTATED reason: Mark as over-annotated. Specific interaction biology should be represented as TRAPP/TRAPPII/TRAPPIII complex membership and TRAPP/RAB1 trafficking context, not generic GO:0005515. - term: id: GO:0005515 label: protein binding evidence_type: IPI original_reference_id: PMID:32296183 qualifier: enables review: summary: Generic protein binding is not informative for TRAPPC3. action: MARK_AS_OVER_ANNOTATED reason: Mark as over-annotated. Specific interaction biology should be represented as TRAPP/TRAPPII/TRAPPIII complex membership and TRAPP/RAB1 trafficking context, not generic GO:0005515. - term: id: GO:0005515 label: protein binding evidence_type: IPI original_reference_id: PMID:33961781 qualifier: enables review: summary: Generic protein binding is not informative for TRAPPC3. action: MARK_AS_OVER_ANNOTATED reason: Mark as over-annotated. Specific interaction biology should be represented as TRAPP/TRAPPII/TRAPPIII complex membership and TRAPP/RAB1 trafficking context, not generic GO:0005515. - term: id: GO:0005515 label: protein binding evidence_type: IPI original_reference_id: PMID:35271311 qualifier: enables review: summary: Generic protein binding is not informative for TRAPPC3. action: MARK_AS_OVER_ANNOTATED reason: Mark as over-annotated. Specific interaction biology should be represented as TRAPP/TRAPPII/TRAPPIII complex membership and TRAPP/RAB1 trafficking context, not generic GO:0005515. - term: id: GO:0000139 label: Golgi membrane evidence_type: IEA original_reference_id: GO_REF:0000107 qualifier: located_in review: summary: Golgi membrane localization is consistent with TRAPPC3/Bet3 role in TRAPP trafficking complexes. action: ACCEPT reason: Accept as a more specific Golgi location for the TRAPP trafficking role. additional_reference_ids: - PMID:21453443 - PMID:18930054 supported_by: - *id006 - *id007 - term: id: GO:0005829 label: cytosol evidence_type: IEA original_reference_id: GO_REF:0000107 qualifier: located_in review: summary: TRAPPC3-containing TRAPP reactions occur on the cytosolic/cytoplasmic side of ER-Golgi trafficking membranes. action: ACCEPT reason: Accept as supported location for a peripheral trafficking-complex subunit. additional_reference_ids: - Reactome:R-HSA-5694409 - Reactome:R-HSA-5694439 - Reactome:R-HSA-8877475 supported_by: - *id003 - *id001 - *id002 - term: id: GO:0005737 label: cytoplasm evidence_type: NAS original_reference_id: PMID:27066478 qualifier: located_in review: summary: TRAPPC3-containing TRAPP reactions occur on the cytosolic/cytoplasmic side of ER-Golgi trafficking membranes. action: ACCEPT reason: Accept as supported location for a peripheral trafficking-complex subunit. additional_reference_ids: - Reactome:R-HSA-5694409 - Reactome:R-HSA-5694439 - Reactome:R-HSA-8877475 supported_by: - *id003 - *id001 - *id002 - term: id: GO:0006888 label: endoplasmic reticulum to Golgi vesicle-mediated transport evidence_type: NAS original_reference_id: PMID:27066478 qualifier: involved_in review: summary: TRAPPC3-containing TRAPP complexes mediate ER-to-Golgi vesicle traffic through TRAPP/RAB1 biology. action: ACCEPT reason: Accept as a core process for TRAPPC3. Multiple human/mammalian TRAPP sources and Reactome support ER-to-Golgi trafficking. additional_reference_ids: - PMID:18930054 - PMID:21525244 - Reactome:R-HSA-5694439 - Reactome:R-HSA-8877475 supported_by: - *id004 - *id011 - *id003 - *id001 - term: id: GO:0006901 label: vesicle coat assembly evidence_type: NAS original_reference_id: PMID:27066478 qualifier: involved_in review: summary: TRAPPC3 interacts with COPII/SEC23-associated ER-derived vesicle trafficking machinery, but it is not a vesicle coat assembly factor. action: MODIFY reason: Modify to ER-to-Golgi vesicle-mediated transport to capture the supported trafficking role without overclaiming coat assembly. proposed_replacement_terms: - &id012 id: GO:0006888 label: endoplasmic reticulum to Golgi vesicle-mediated transport additional_reference_ids: - Reactome:R-HSA-5694439 - Reactome:R-HSA-8877475 supported_by: - *id005 - &id013 reference_id: Reactome:R-HSA-8877475 supporting_text: TRAPPCII is recruited to ER-derived vesicles by virtue of an interaction between the TRAPPCII component TRAPPC3 and the COPII coat protein SEC23 - term: id: GO:0048208 label: COPII vesicle coat assembly evidence_type: NAS original_reference_id: PMID:27066478 qualifier: involved_in review: summary: The COPII evidence supports TRAPPC3-SEC23 recruitment to ER-derived vesicles, not direct COPII coat assembly by TRAPPC3. action: MODIFY reason: Modify to ER-to-Golgi vesicle-mediated transport. proposed_replacement_terms: - *id012 additional_reference_ids: - Reactome:R-HSA-5694439 - Reactome:R-HSA-8877475 supported_by: - *id005 - *id013 - term: id: GO:0099022 label: obsolete vesicle tethering evidence_type: NAS original_reference_id: PMID:27066478 qualifier: involved_in review: summary: This obsolete vesicle-tethering annotation should not be kept as-is, and direct mammalian TRAPP tethering evidence remains unresolved. action: MODIFY reason: Modify to ER-to-Golgi vesicle-mediated transport, the safer supported TRAPPC3 process. proposed_replacement_terms: - *id012 additional_reference_ids: - PMID:27066478 - PMID:21525244 - Reactome:R-HSA-5694439 supported_by: - reference_id: PMID:27066478 supporting_text: evidence that any TRAPP complex acts as a membrane tether is currently inconclusive - reference_id: PMID:21525244 supporting_text: Direct demonstration of mammalian TRAPP as a vesicle tether has yet to be shown - *id003 - term: id: GO:1990071 label: TRAPPII protein complex evidence_type: NAS original_reference_id: PMID:27066478 qualifier: part_of review: summary: TRAPPC3 is represented in TRAPPII complex models and ComplexPortal annotations. action: ACCEPT reason: Accept as supported TRAPP subtype membership; process-level claims should remain tied to TRAPP/RAB1 trafficking. additional_reference_ids: - PMID:21453443 - PMID:27066478 - Reactome:R-HSA-8877475 supported_by: - *id006 - *id002 - term: id: GO:1990072 label: TRAPPIII protein complex evidence_type: NAS original_reference_id: PMID:27066478 qualifier: part_of review: summary: TRAPPC3 is represented in TRAPPIII complex models, which are relevant to the PN autophagy-recruitment context. action: ACCEPT reason: Accept as supported complex membership while keeping autophagy as context rather than assigning a broad autophagy BP. additional_reference_ids: - PMID:27066478 - Reactome:R-HSA-8877475 supported_by: - reference_id: Reactome:R-HSA-8877475 supporting_text: RAB1 and the TRAPPCIII complex play a role in the formation of the pre-autophagosomal structure (PAS) and contribute to the localization of ATG9 - reference_id: PMID:27066478 supporting_text: the connection of the mammalian TRAPP III complex to autophagy is currently not clear - term: id: GO:0005515 label: protein binding evidence_type: IPI original_reference_id: PMID:21525244 qualifier: enables review: summary: Generic protein binding is not informative for TRAPPC3. action: MARK_AS_OVER_ANNOTATED reason: Mark as over-annotated. Specific interaction biology should be represented as TRAPP/TRAPPII/TRAPPIII complex membership and TRAPP/RAB1 trafficking context, not generic GO:0005515. - term: id: GO:0030008 label: TRAPP complex evidence_type: IDA original_reference_id: PMID:21525244 qualifier: part_of review: summary: TRAPPC3/Bet3 is a core TRAPP complex subunit. action: ACCEPT reason: Accept as core cellular-component membership. This is the cleanest gene-level representation of the PN TRAPP component leaf. additional_reference_ids: - PMID:16828797 - PMID:21525244 - PMID:27066478 supported_by: - *id008 - *id009 - *id010 - term: id: GO:0005829 label: cytosol evidence_type: TAS original_reference_id: Reactome:R-HSA-5694409 qualifier: located_in review: summary: TRAPPC3-containing TRAPP reactions occur on the cytosolic/cytoplasmic side of ER-Golgi trafficking membranes. action: ACCEPT reason: Accept as supported location for a peripheral trafficking-complex subunit. additional_reference_ids: - Reactome:R-HSA-5694409 - Reactome:R-HSA-5694439 - Reactome:R-HSA-8877475 supported_by: - *id003 - *id001 - *id002 - term: id: GO:0005829 label: cytosol evidence_type: TAS original_reference_id: Reactome:R-HSA-5694418 qualifier: located_in review: summary: TRAPPC3-containing TRAPP reactions occur on the cytosolic/cytoplasmic side of ER-Golgi trafficking membranes. action: ACCEPT reason: Accept as supported location for a peripheral trafficking-complex subunit. additional_reference_ids: - Reactome:R-HSA-5694409 - Reactome:R-HSA-5694439 - Reactome:R-HSA-8877475 supported_by: - *id003 - *id001 - *id002 - term: id: GO:0005829 label: cytosol evidence_type: TAS original_reference_id: Reactome:R-HSA-5694439 qualifier: located_in review: summary: TRAPPC3-containing TRAPP reactions occur on the cytosolic/cytoplasmic side of ER-Golgi trafficking membranes. action: ACCEPT reason: Accept as supported location for a peripheral trafficking-complex subunit. additional_reference_ids: - Reactome:R-HSA-5694409 - Reactome:R-HSA-5694439 - Reactome:R-HSA-8877475 supported_by: - *id003 - *id001 - *id002 - term: id: GO:0005829 label: cytosol evidence_type: TAS original_reference_id: Reactome:R-HSA-5694441 qualifier: located_in review: summary: TRAPPC3-containing TRAPP reactions occur on the cytosolic/cytoplasmic side of ER-Golgi trafficking membranes. action: ACCEPT reason: Accept as supported location for a peripheral trafficking-complex subunit. additional_reference_ids: - Reactome:R-HSA-5694409 - Reactome:R-HSA-5694439 - Reactome:R-HSA-8877475 supported_by: - *id003 - *id001 - *id002 - term: id: GO:0005829 label: cytosol evidence_type: TAS original_reference_id: Reactome:R-HSA-8877475 qualifier: located_in review: summary: TRAPPC3-containing TRAPP reactions occur on the cytosolic/cytoplasmic side of ER-Golgi trafficking membranes. action: ACCEPT reason: Accept as supported location for a peripheral trafficking-complex subunit. additional_reference_ids: - Reactome:R-HSA-5694409 - Reactome:R-HSA-5694439 - Reactome:R-HSA-8877475 supported_by: - *id003 - *id001 - *id002 references: - id: GO_REF:0000002 title: Gene Ontology annotation through association of InterPro records with GO terms findings: [] - id: GO_REF:0000033 title: Annotation inferences using phylogenetic trees findings: [] - id: GO_REF:0000044 title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt findings: [] - id: GO_REF:0000107 title: Automatic transfer of experimentally verified manual GO annotation data to orthologs using Ensembl Compara findings: [] - id: GO_REF:0000120 title: Combined Automated Annotation using Multiple IEA Methods findings: [] - id: PMID:16189514 title: Towards a proteome-scale map of the human protein-protein interaction network. findings: [] - id: PMID:16828797 title: 'Structure of the Bet3-Tpc6B core of TRAPP: two Tpc6 paralogs form trimeric complexes with Bet3 and Mum2.' findings: [] - id: PMID:16908848 title: 'Unique self-palmitoylation activity of the transport protein particle component Bet3: a mechanism required for protein stability.' findings: [] - id: PMID:18930054 title: Distinct isocomplexes of the TRAPP trafficking factor coexist inside human cells. findings: [] - id: PMID:21453443 title: Organization and assembly of the TRAPPII complex. findings: [] - id: PMID:21525244 title: C4orf41 and TTC-15 are mammalian TRAPP components with a role at an early stage in ER-to-Golgi trafficking. findings: [] - id: PMID:21827752 title: A yeast two hybrid screen identifies SPATA4 as a TRAPP interactor. findings: [] - id: PMID:25416956 title: A proteome-scale map of the human interactome network. findings: [] - id: PMID:27066478 title: TRAPP Complexes in Secretion and Autophagy. findings: [] - id: PMID:28514442 title: Architecture of the human interactome defines protein communities and disease networks. findings: [] - id: PMID:31515488 title: Extensive disruption of protein interactions by genetic variants across the allele frequency spectrum in human populations. findings: [] - id: PMID:32296183 title: A reference map of the human binary protein interactome. findings: [] - id: PMID:33961781 title: Dual proteome-scale networks reveal cell-specific remodeling of the human interactome. findings: [] - id: PMID:35271311 title: 'OpenCell: Endogenous tagging for the cartography of human cellular organization.' findings: [] - id: Reactome:R-HSA-5694409 title: Nucleotide exchange on RAB1 findings: [] - id: Reactome:R-HSA-5694418 title: RAB1:GTP binds USO1 and GORASP1:GOLGA2 findings: [] - id: Reactome:R-HSA-5694439 title: COPII coat binds TRAPPCII and RAB1:GDP findings: [] - id: Reactome:R-HSA-5694441 title: CSNK1D phosphorylates SEC23 findings: [] - id: Reactome:R-HSA-8877475 title: TRAPPC complexes exchange GTP for GDP on RAB1 findings: [] core_functions: - contributes_to_molecular_function: id: GO:0005085 label: guanyl-nucleotide exchange factor activity in_complex: id: GO:0030008 label: TRAPP complex description: TRAPPC3 contributes the Bet3 core subunit to TRAPP complexes, supporting complex-level RAB1 guanine-nucleotide exchange and ER-to-Golgi trafficking. It should be modeled as contributing to the TRAPP complex activity rather than independently enabling GEF activity. directly_involved_in: - id: GO:0006888 label: endoplasmic reticulum to Golgi vesicle-mediated transport locations: - id: GO:0005829 label: cytosol - id: GO:0005737 label: cytoplasm - id: GO:0033106 label: cis-Golgi network membrane - id: GO:0000139 label: Golgi membrane - id: GO:0005783 label: endoplasmic reticulum - id: GO:0005794 label: Golgi apparatus supported_by: - *id008 - *id009 - *id010 - *id001 - *id002 - *id014 - *id004 - *id011 - *id003 - *id005 proposed_new_terms: [] suggested_questions: - question: Should TRAPPC3 and related TRAPP core subunits retain contributes_to RAB1 GEF annotations even when the complex-level catalytic subunit assignment is not fully resolved? experts: - GO transport editors - Reactome TRAPP curators - question: Should TRAPPIII complex membership be considered sufficient for PN autophagophore-recruitment context without assigning broad autophagy process terms? experts: - GO autophagy editors - ComplexPortal curators - question: Should TRAPPC3 coat-assembly annotations be replaced by ER-to-Golgi vesicle-mediated transport or by a more specific TRAPPC/COPII recruitment term if one exists? experts: - GO transport editors - ComplexPortal curators suggested_experiments: - description: Reconstitute TRAPPC3-containing TRAPP complexes and measure RAB1 GDP-GTP exchange with TRAPPC3 depletion/rescue or interface mutants. experiment_type: complex reconstitution and RAB1 GEF assay hypothesis: TRAPPC3 is required as a core TRAPP subunit for complex-level RAB1 GEF activity. - description: Test TRAPPC3 mutants that disrupt TRAPPC6/TRAPPC1 interfaces for effects on ER-to-Golgi cargo trafficking, SEC23/COPII association, and Golgi membrane recruitment. experiment_type: trafficking rescue and complex-interface assay hypothesis: TRAPPC3 scaffolding of core TRAPP interactions is required for ER-to-Golgi vesicle-mediated transport. - description: Separate TRAPPII and TRAPPIII pools in TRAPPC3 rescue cells and assay ATG9 localization plus canonical ER-to-Golgi transport in parallel. experiment_type: TRAPP subtype-specific autophagy/traffic assay hypothesis: TRAPPC3 autophagy phenotypes depend on TRAPPIII/RAB1 context and should be distinguished from core ER-to-Golgi transport defects.