id: Q8WVT3 gene_symbol: TRAPPC12 product_type: PROTEIN status: COMPLETE taxon: id: NCBITaxon:9606 label: Homo sapiens description: >- TRAPPC12/TRAMM/TTC-15 is a moonlighting metazoan TRAPP/TRAPPIII-associated protein. In interphase it participates in TRAPP-dependent early secretory traffic between ER, ERGIC, and Golgi. During mitosis it leaves the TRAPP context and supports chromosome congression, kinetochore stability, and CENP-E recruitment. Its shared cellular roles are TRAPP/TRAPPII/TRAPPIII complex membership and TRAPP/RAB1 trafficking; direct TRAPPC12-specific autophagy evidence is limited. existing_annotations: - term: id: GO:0005794 label: Golgi apparatus evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: is_active_in review: summary: Golgi apparatus localization/activity context is supported for TRAPPC12/TRAPP trafficking. action: ACCEPT reason: Accept as supported location/context. TRAPPC12 is mainly observed in Golgi/perinuclear TRAPP context, and TRAPPC12 disease fibroblasts show rescued Golgi fragmentation and delayed ER-to-Golgi/Golgi transport. additional_reference_ids: - PMID:21525244 - PMID:28777934 - file:human/TRAPPC12/TRAPPC12-uniprot.txt supported_by: - &id004 reference_id: PMID:21525244 supporting_text: C12 is largely found in punctae throughout the cell - &id003 reference_id: PMID:21525244 supporting_text: highly punctate with an obvious concentration of the punctae in the perinuclear region - &id015 reference_id: PMID:21525244 supporting_text: RNAi against C8, C11, or C12 resulted in Golgi fragmentation - &id016 reference_id: PMID:28777934 supporting_text: Fibroblasts derived from all three individuals showed a fragmented Golgi - &id007 reference_id: PMID:28777934 supporting_text: Protein transport from the endoplasmic reticulum to and through the Golgi was delayed - term: id: GO:0030008 label: TRAPP complex evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: part_of review: summary: TRAPPC12 is a mammalian TRAPP complex component. action: ACCEPT reason: Accept as core cellular-component membership. TRAPPC12/TTC-15 is identified as a stable mammalian TRAPP interactor, and UniProt describes it as a component of the multisubunit TRAPP complex. additional_reference_ids: - PMID:21525244 - file:human/TRAPPC12/TRAPPC12-uniprot.txt - PMID:25918224 supported_by: - &id022 reference_id: PMID:21525244 supporting_text: TTC-15 (now designated TRAPPC12) - &id001 reference_id: PMID:21525244 supporting_text: C4orf41 and TTC-15 interact both with each other and with previously characterized TRAPP subunits - &id002 reference_id: PMID:21525244 supporting_text: These results firmly establish the newly identified proteins as stable TRAPP interactors - &id023 reference_id: PMID:21525244 supporting_text: endogenous C12 was observed to elute in the same high-molecular-weight pool as TRAPP - &id024 reference_id: file:human/TRAPPC12/TRAPPC12-uniprot.txt supporting_text: Component of the multisubunit TRAPP (transport protein - &id025 reference_id: PMID:25918224 supporting_text: TRAMM cycles between its role in TRAPP in interphase cells - term: id: GO:0005634 label: nucleus evidence_type: IEA original_reference_id: GO_REF:0000044 qualifier: located_in review: summary: Nuclear localization is supported for the mitotic TRAMM/TRAPPC12 branch. action: ACCEPT reason: Accept as a supported location for the moonlighting mitotic role. TRAMM cofractionates with a nuclear marker, associates weakly with mitotic chromosomes/kinetochores, and UniProt cites nuclear localization from PMID:25918224. additional_reference_ids: - PMID:25918224 - file:human/TRAPPC12/TRAPPC12-uniprot.txt supported_by: - &id011 reference_id: PMID:25918224 supporting_text: cellular fractionation indicated that a small but reproducible amount of TRAMM cofractionated with a nuclear marker - &id012 reference_id: PMID:25918224 supporting_text: Small amounts of TRAMM associated with chromosomes - &id013 reference_id: PMID:25918224 supporting_text: small amounts of TRAMM on chromosomes associate with ACA-positive structures representing the kinetochore - &id014 reference_id: file:human/TRAPPC12/TRAPPC12-uniprot.txt supporting_text: Nucleus {ECO:0000269|PubMed:25918224} - term: id: GO:0005793 label: endoplasmic reticulum-Golgi intermediate compartment evidence_type: IEA original_reference_id: GO_REF:0000044 qualifier: located_in review: summary: ERGIC localization/colocalization is supported for early TRAPP secretory traffic. action: ACCEPT reason: Accept as supported location/context. TRAPPC12/C12 is part of the TRAPP early secretory pathway, and C11/C12 depletion arrests VSV-G cargo in a BFA-resistant ERGIC-associated compartment. additional_reference_ids: - PMID:21525244 - file:human/TRAPPC12/TRAPPC12-uniprot.txt supported_by: - &id005 reference_id: PMID:21525244 supporting_text: knockdowns of either C11 or C12 arrest a cargo protein in a BFA-resistant compartment - &id006 reference_id: PMID:21525244 supporting_text: TRAPP functions either at ER exit sites or at peripheral ERGIC (BFA-resistant) elements - &id019 reference_id: file:human/TRAPPC12/TRAPPC12-uniprot.txt supporting_text: Endoplasmic reticulum-Golgi intermediate - 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 TRAPPC12 function. action: MARK_AS_OVER_ANNOTATED reason: Mark as over-annotated. TRAPPC12 interactions are better represented as TRAPP/TRAPPIII complex membership or as CENP-E recruitment to kinetochore, not as generic protein binding. additional_reference_ids: - PMID:21525244 - PMID:25918224 - PMID:32296183 supported_by: - *id001 - *id002 - &id017 reference_id: PMID:25918224 supporting_text: prevented the recruitment of CENP-E to the kinetochore - &id018 reference_id: PMID:25918224 supporting_text: TRAMM-5D was able to recruit more CENP-E to kinetochores - term: id: GO:0005737 label: cytoplasm evidence_type: NAS original_reference_id: PMID:27066478 qualifier: located_in review: summary: Cytoplasm is a broad but reasonable location for TRAPPC12 soluble/peripheral TRAPP biology. action: ACCEPT reason: Accept as broad supported location/context. TRAPPC12 has cytoplasmic/perinuclear/Golgi pools in early secretory traffic and a distinct mitotic pool. additional_reference_ids: - PMID:21525244 - PMID:25918224 - Reactome:R-HSA-8877475 supported_by: - *id003 - *id004 - reference_id: PMID:25918224 supporting_text: the supernatant was kept as the cytoplasmic fraction - &id028 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 - 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: TRAPPC12 participates in early secretory ER-to-ERGIC/Golgi transport through TRAPP/TRAPPIII. action: ACCEPT reason: Accept as a core process. Direct TRAPPC12 evidence supports early ER-to-Golgi trafficking, ERGIC cargo arrest, Golgi fragmentation on depletion, and delayed ER-to-Golgi/Golgi transport in patient fibroblasts. additional_reference_ids: - PMID:21525244 - PMID:28777934 - Reactome:R-HSA-8877475 - file:human/TRAPPC12/TRAPPC12-uniprot.txt supported_by: - &id008 reference_id: PMID:21525244 supporting_text: ER-to-Golgi trafficking at a very early stage - *id005 - *id006 - &id020 reference_id: PMID:21525244 supporting_text: These results imply that the three novel TRAPP-associated proteins function in the early secretory pathway - *id007 - &id021 reference_id: file:human/TRAPPC12/TRAPPC12-uniprot.txt supporting_text: endoplasmic reticulum to Golgi apparatus trafficking at a very early - &id009 reference_id: Reactome:R-HSA-8877475 supporting_text: RAB1 is involved in COPII-mediated anterograde traffic from the endoplasmic reticulum to the ERGIC - term: id: GO:0048208 label: COPII vesicle coat assembly evidence_type: NAS original_reference_id: PMID:27066478 qualifier: involved_in review: summary: The COPII coat assembly annotation captures early secretory context but overstates TRAPPC12 as a coat-assembly factor. action: MODIFY reason: Modify to ER-to-Golgi vesicle-mediated transport. TRAPPC12 evidence supports early ER/ERGIC/Golgi trafficking in COPII-associated anterograde traffic, not direct assembly of the COPII vesicle coat. proposed_replacement_terms: - &id010 id: GO:0006888 label: endoplasmic reticulum to Golgi vesicle-mediated transport additional_reference_ids: - PMID:21525244 - PMID:28777934 - Reactome:R-HSA-8877475 supported_by: - *id008 - *id005 - *id006 - *id007 - *id009 - term: id: GO:0099022 label: obsolete vesicle tethering evidence_type: NAS original_reference_id: PMID:27066478 qualifier: involved_in review: summary: The obsolete vesicle-tethering annotation should not be retained as-is. action: MODIFY reason: Modify to ER-to-Golgi vesicle-mediated transport, the supported TRAPPC12/TRAPP process. Mammalian TRAPP tethering remains unresolved and this GO term is obsolete. proposed_replacement_terms: - *id010 additional_reference_ids: - PMID:27066478 - PMID:21525244 - PMID:28777934 supported_by: - reference_id: PMID:27066478 supporting_text: evidence that any TRAPP complex acts as a membrane tether is currently inconclusive - *id008 - *id006 - *id007 - term: id: GO:1990072 label: TRAPPIII protein complex evidence_type: NAS original_reference_id: PMID:27066478 qualifier: part_of review: summary: TRAPPC12 is modeled as a mammalian TRAPPIII-associated subunit. action: ACCEPT reason: Accept as core complex membership in the PN TRAPP bucket. The review literature assigns TRAPPC12 to mammalian TRAPPIII, and Reactome models TRAPPCIII in RAB1/autophagy context. additional_reference_ids: - PMID:27066478 - PMID:21525244 - Reactome:R-HSA-8877475 supported_by: - &id029 reference_id: PMID:27066478 supporting_text: TRAPP III, which contains core TRAPP plus TrappC8, 11-13 - *id001 - *id002 - 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) - term: id: GO:0005654 label: nucleoplasm evidence_type: IDA original_reference_id: GO_REF:0000052 qualifier: located_in review: summary: Nucleoplasm is more specific than the accessible TRAMM/TRAPPC12 evidence supports. action: MODIFY reason: Modify to nucleus. The seeded HPA-derived row may reflect nuclear immunofluorescence, but the accessible full-text evidence supports nuclear/chromosome/kinetochore association rather than nucleoplasm specifically. proposed_replacement_terms: - id: GO:0005634 label: nucleus additional_reference_ids: - PMID:25918224 - file:human/TRAPPC12/TRAPPC12-uniprot.txt supported_by: - *id011 - *id012 - *id013 - *id014 - term: id: GO:0005794 label: Golgi apparatus evidence_type: IDA original_reference_id: GO_REF:0000052 qualifier: located_in review: summary: Golgi apparatus localization/activity context is supported for TRAPPC12/TRAPP trafficking. action: ACCEPT reason: Accept as supported location/context. TRAPPC12 is mainly observed in Golgi/perinuclear TRAPP context, and TRAPPC12 disease fibroblasts show rescued Golgi fragmentation and delayed ER-to-Golgi/Golgi transport. additional_reference_ids: - PMID:21525244 - PMID:28777934 - file:human/TRAPPC12/TRAPPC12-uniprot.txt supported_by: - *id004 - *id003 - *id015 - *id016 - *id007 - 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 TRAPPC12 function. action: MARK_AS_OVER_ANNOTATED reason: Mark as over-annotated. TRAPPC12 interactions are better represented as TRAPP/TRAPPIII complex membership or as CENP-E recruitment to kinetochore, not as generic protein binding. additional_reference_ids: - PMID:21525244 - PMID:25918224 - PMID:32296183 supported_by: - *id001 - *id002 - *id017 - *id018 - term: id: GO:0005793 label: endoplasmic reticulum-Golgi intermediate compartment evidence_type: IMP original_reference_id: PMID:21525244 qualifier: colocalizes_with review: summary: ERGIC localization/colocalization is supported for early TRAPP secretory traffic. action: ACCEPT reason: Accept as supported location/context. TRAPPC12/C12 is part of the TRAPP early secretory pathway, and C11/C12 depletion arrests VSV-G cargo in a BFA-resistant ERGIC-associated compartment. additional_reference_ids: - PMID:21525244 - file:human/TRAPPC12/TRAPPC12-uniprot.txt supported_by: - *id005 - *id006 - *id019 - term: id: GO:0006888 label: endoplasmic reticulum to Golgi vesicle-mediated transport evidence_type: IMP original_reference_id: PMID:21525244 qualifier: involved_in review: summary: TRAPPC12 participates in early secretory ER-to-ERGIC/Golgi transport through TRAPP/TRAPPIII. action: ACCEPT reason: Accept as a core process. Direct TRAPPC12 evidence supports early ER-to-Golgi trafficking, ERGIC cargo arrest, Golgi fragmentation on depletion, and delayed ER-to-Golgi/Golgi transport in patient fibroblasts. additional_reference_ids: - PMID:21525244 - PMID:28777934 - Reactome:R-HSA-8877475 - file:human/TRAPPC12/TRAPPC12-uniprot.txt supported_by: - *id008 - *id005 - *id006 - *id020 - *id007 - *id021 - *id009 - term: id: GO:0007030 label: Golgi organization evidence_type: IMP original_reference_id: PMID:21525244 qualifier: involved_in review: summary: Golgi organization is a direct TRAPPC12-depletion/disease phenotype but is secondary to early secretory trafficking. action: KEEP_AS_NON_CORE reason: Keep as non-core. Golgi fragmentation is a useful readout of TRAPPC12/TRAPP disruption and is disease-relevant, while the core process is ER-to-ERGIC/Golgi trafficking. additional_reference_ids: - PMID:21525244 - PMID:28777934 supported_by: - *id015 - *id016 - *id020 - term: id: GO:0048471 label: perinuclear region of cytoplasm evidence_type: IMP original_reference_id: PMID:21525244 qualifier: colocalizes_with review: summary: Perinuclear cytoplasmic localization is supported for interphase TRAPPC12/Golgi puncta. action: ACCEPT reason: Accept as a supported location for the interphase trafficking pool of TRAPPC12. additional_reference_ids: - PMID:21525244 - PMID:25918224 supported_by: - *id003 - *id004 - reference_id: PMID:25918224 supporting_text: TRAMM is largely localized to a perinuclear region representing the Golgi - term: id: GO:0030008 label: TRAPP complex evidence_type: IDA original_reference_id: PMID:21525244 qualifier: part_of review: summary: TRAPPC12 is a mammalian TRAPP complex component. action: ACCEPT reason: Accept as core cellular-component membership. TRAPPC12/TTC-15 is identified as a stable mammalian TRAPP interactor, and UniProt describes it as a component of the multisubunit TRAPP complex. additional_reference_ids: - PMID:21525244 - file:human/TRAPPC12/TRAPPC12-uniprot.txt - PMID:25918224 supported_by: - *id022 - *id001 - *id002 - *id023 - *id024 - *id025 - term: id: GO:0000776 label: kinetochore evidence_type: IDA original_reference_id: PMID:25918224 qualifier: located_in review: summary: Kinetochore localization is weak/transient but directly supported for mitotic TRAMM/TRAPPC12. action: ACCEPT reason: Accept as supported. The full-text paper shows small amounts of TRAMM on chromosomes associated with ACA-positive kinetochore structures and frames this as a weak/transient kinetochore association. additional_reference_ids: - PMID:25918224 - file:human/TRAPPC12/TRAPPC12-uniprot.txt supported_by: - *id012 - *id013 - &id032 reference_id: PMID:25918224 supporting_text: TRAMM appears to have a weak or transient association with kinetochores - &id026 reference_id: file:human/TRAPPC12/TRAPPC12-uniprot.txt supporting_text: the recruitment of CENPE to the kinetochores - term: id: GO:0005515 label: protein binding evidence_type: IPI original_reference_id: PMID:25918224 qualifier: enables review: summary: Generic protein binding is not informative for TRAPPC12 function. action: MARK_AS_OVER_ANNOTATED reason: Mark as over-annotated. TRAPPC12 interactions are better represented as TRAPP/TRAPPIII complex membership or as CENP-E recruitment to kinetochore, not as generic protein binding. additional_reference_ids: - PMID:21525244 - PMID:25918224 - PMID:32296183 supported_by: - *id001 - *id002 - *id017 - *id018 - term: id: GO:0005634 label: nucleus evidence_type: IDA original_reference_id: PMID:25918224 qualifier: located_in review: summary: Nuclear localization is supported for the mitotic TRAMM/TRAPPC12 branch. action: ACCEPT reason: Accept as a supported location for the moonlighting mitotic role. TRAMM cofractionates with a nuclear marker, associates weakly with mitotic chromosomes/kinetochores, and UniProt cites nuclear localization from PMID:25918224. additional_reference_ids: - PMID:25918224 - file:human/TRAPPC12/TRAPPC12-uniprot.txt supported_by: - *id011 - *id012 - *id013 - *id014 - term: id: GO:0051310 label: metaphase chromosome alignment evidence_type: IMP original_reference_id: PMID:25918224 qualifier: involved_in review: summary: TRAPPC12/TRAMM is directly involved in metaphase chromosome alignment/congression. action: ACCEPT reason: Accept as a core moonlighting mitotic process. TRAMM depletion causes noncongressed chromosomes, mitotic arrest, and a phenotype similar to CENP-E depletion. additional_reference_ids: - PMID:25918224 - file:human/TRAPPC12/TRAPPC12-uniprot.txt supported_by: - &id030 reference_id: PMID:25918224 supporting_text: Depletion of TRAMM resulted in noncongressed chromosomes - &id031 reference_id: PMID:25918224 supporting_text: arrested cells in mitosis - reference_id: PMID:25918224 supporting_text: TRAMM and CENP-E may act together in chromosome congression - *id026 - term: id: GO:0090234 label: regulation of kinetochore assembly evidence_type: IMP original_reference_id: PMID:25918224 qualifier: involved_in review: summary: TRAPPC12/TRAMM regulates kinetochore assembly/stability during mitosis. action: ACCEPT reason: Accept as a core moonlighting mitotic process. TRAMM depletion alters kinetochore protein localization and the authors identify TRAMM as a regulator of kinetochore stability. additional_reference_ids: - PMID:25918224 - file:human/TRAPPC12/TRAPPC12-uniprot.txt supported_by: - reference_id: PMID:25918224 supporting_text: kinetochore stability and CENP-E recruitment - &id027 reference_id: PMID:25918224 supporting_text: TRAMM affects the localization of some components of the outer layer of the kinetochore - *id013 - *id026 - term: id: GO:1905342 label: positive regulation of protein localization to kinetochore evidence_type: IMP original_reference_id: PMID:25918224 qualifier: involved_in review: summary: TRAPPC12/TRAMM promotes CENP-E localization to kinetochores. action: ACCEPT reason: Accept as a core moonlighting mitotic process. TRAMM depletion prevents CENP-E recruitment, and phosphomimetic TRAMM recruits more CENP-E to kinetochores than the nonphosphorylatable mutant. additional_reference_ids: - PMID:25918224 - file:human/TRAPPC12/TRAPPC12-uniprot.txt supported_by: - *id017 - *id018 - *id027 - *id026 - term: id: GO:0005829 label: cytosol evidence_type: TAS original_reference_id: Reactome:R-HSA-8877475 qualifier: located_in review: summary: Cytosol is consistent with TRAPPC12-containing TRAPP trafficking reactions. action: ACCEPT reason: Accept as supported location/context for soluble/peripheral TRAPP complex biology. additional_reference_ids: - PMID:21525244 - Reactome:R-HSA-8877475 supported_by: - *id023 - *id028 references: - 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:0000052 title: Gene Ontology annotation based on curation of immunofluorescence data 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:25918224 title: TRAMM/TrappC12 plays a role in chromosome congression, kinetochore stability, and CENP-E recruitment. findings: [] - id: PMID:27066478 title: TRAPP Complexes in Secretion and Autophagy. findings: [] - id: PMID:32296183 title: A reference map of the human binary protein interactome. findings: [] - id: Reactome:R-HSA-8877475 title: TRAPPC complexes exchange GTP for GDP on RAB1 findings: [] - id: PMID:28777934 title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction. findings: [] - id: file:human/TRAPPC12/TRAPPC12-uniprot.txt title: UniProtKB record for TRAPPC12 findings: [] core_functions: - contributes_to_molecular_function: id: GO:0005085 label: guanyl-nucleotide exchange factor activity in_complex: id: GO:1990072 label: TRAPPIII protein complex description: Interphase TRAPPC12 contributes a TRAPP/TRAPPIII-associated subunit to complex-level RAB1 GEF trafficking between ER, ERGIC, and Golgi. This is the proteostasis-network TRAPP-component role and should be modeled as complex contribution rather than independent GEF activity or COPII coat assembly. directly_involved_in: - *id010 locations: - id: GO:0005829 label: cytosol - id: GO:0005737 label: cytoplasm - id: GO:0005793 label: endoplasmic reticulum-Golgi intermediate compartment - id: GO:0005794 label: Golgi apparatus - id: GO:0048471 label: perinuclear region of cytoplasm supported_by: - *id028 - *id029 - *id001 - *id002 - *id023 - *id008 - *id005 - *id006 - *id015 - *id007 - description: Mitotic TRAPPC12/TRAMM functions outside the interphase TRAPP pool to support chromosome congression, kinetochore stability/assembly, and recruitment of CENP-E to kinetochores. This is a direct moonlighting role and is not the PN TRAPP-component propagation target. directly_involved_in: - id: GO:0051310 label: metaphase chromosome alignment - id: GO:0090234 label: regulation of kinetochore assembly - id: GO:1905342 label: positive regulation of protein localization to kinetochore locations: - id: GO:0005634 label: nucleus - id: GO:0000776 label: kinetochore supported_by: - *id030 - *id031 - *id012 - *id013 - *id027 - *id017 - *id018 - *id032 - *id025 proposed_new_terms: [] suggested_questions: - question: Should TRAPPC12/TRAMM be represented in GO-CAM as two separable functional contexts, interphase TRAPP trafficking and mitotic kinetochore/CENP-E recruitment? experts: - GO transport editors - GO cell-cycle editors - Reactome TRAPP curators - question: Should generic protein binding annotations for TRAPPC12-CENP-E and TRAPPC12-TRAPP interactions be replaced by more informative kinetochore-localization and TRAPP-complex annotations? experts: - GO molecular function editors - GO cell-cycle editors - question: Does direct evidence support a TRAPPC12-specific autophagy process annotation, or should PN autophagy context remain limited to TRAPPIII/TRAPP complex membership? experts: - GO autophagy editors - TRAPP/autophagy domain experts suggested_experiments: - description: Use synchronized cells with TRAPPC12 knockdown/rescue and phosphosite mutants to measure TRAPP complex association, ER-Golgi cargo transport, Golgi morphology, CENP-E kinetochore recruitment, and chromosome congression in matched assays. experiment_type: dual trafficking and mitosis rescue assay hypothesis: TRAPPC12 switches between an interphase TRAPP trafficking role and a mitotic kinetochore/CENP-E recruitment role controlled by phosphorylation and cell-cycle state. - description: Reconstitute TRAPPC12-containing TRAPPIII and measure RAB1 exchange plus TRAPPC12 release or altered association after mitotic phosphorylation mimics. experiment_type: complex reconstitution and RAB1 GEF assay hypothesis: TRAPPC12 contributes to complex-level RAB1 GEF trafficking while phosphorylation changes its TRAPP association during mitosis. - description: Test whether TRAPPC12 depletion affects ATG9 cycling or early autophagy markers independently of ER-Golgi trafficking and mitotic arrest. experiment_type: autophagy trafficking assay hypothesis: If TRAPPC12 has a direct autophagy role, autophagy-initiation defects should be separable from its secretory and mitotic phenotypes.