TRAPPC13/C5orf44 is a Trs65-related large TRAPP subunit curated in human TRAPPII and TRAPPIII complex contexts. Its main role is contribution to TRAPP complex RAB1/Rab GEF trafficking and ER-to-Golgi vesicle-mediated transport, rather than independent GEF activity, COPII coat assembly, generic protein binding, or a direct TRAPPC13-specific autophagy function.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:1990072 TRAPPIII protein complex | IBA GO_REF:0000033 | ACCEPT | Summary: TRAPPC13 is supportable as a mammalian TRAPPIII-associated TRAPP subunit, while its exact TRAPPII/TRAPPIII partition remains source-dependent. Cryo-EM of metazoan TRAPPIII positions TRAPPC13, with TRAPPC12, at the vertex where the TRAPPC8 and TRAPPC11 arms meet, consistent with bona fide TRAPPIII membership. Reason: Accept as PN-relevant complex membership. GO Central, UniProt, and the TRAPP review place human TRAPPC13 in TRAPP complex context, and the review specifically notes mammalian TRAPP III contains core TRAPP plus TrappC8, 11-13. The falcon deep research summarizes Galindo et al. (2021) cryo-EM placing TRAPPC13 as a metazoan TRAPPIII-specific subunit at the arm vertex, providing structural corroboration of TRAPPIII membership. Supporting Evidence: PMID:27066478 TRAPP II, which contains core TRAPP plus TrappC9-10, and TRAPP III, which contains core TRAPP plus TrappC8, 11-13 PMID:27066478 The inclusion of TrappC13, the homolog of Trs65, in the mammalian TRAPP III differs from its inclusion in the yeast TRAPP II complex file:human/TRAPPC13/TRAPPC13-uniprot.txt GO; GO:1990072; C:TRAPPIII protein complex; IBA:GO_Central. Reactome:R-HSA-8877475 RAB1 and the TRAPPCIII complex play a role in the formation of the pre-autophagosomal structure (PAS) file:human/TRAPPC13/TRAPPC13-deep-research-falcon.md High-resolution cryo-EM analysis from Galindo et al. (2021) definitively positioned TRAPPC13, together with TRAPPC12, at the vertex where the TRAPPC8 and TRAPPC11 arms meet |
| GO:0005515 protein binding | IPI PMID:21453443 Organization and assembly of the TRAPPII complex. | MARK AS OVER ANNOTATED | Summary: Generic protein binding is not informative for TRAPPC13 function. The interactions captured are with other TRAPP subunits, consistent with TRAPPC13's role as a structural/accessory subunit positioned at the vertex of the TRAPPIII arms rather than an independent binding partner. Reason: Mark as over-annotated. The PMID:21453443/IntAct evidence reflects interactions with TRAPP components and is better captured as TRAPP complex membership and complex-level trafficking function. The falcon deep research reinforces that TRAPPC13 is best understood as a structural/accessory subunit contributing to complex organization, not via a generic protein-binding function. Supporting Evidence: PMID:21453443 proteins related to Trs85, Trs65 and Tca17 are part of the same TRAPP complex in file:human/TRAPPC13/TRAPPC13-deep-research-falcon.md TRAPPC13 is therefore best understood as a **structural/accessory subunit** rather than the catalytic GEF center. file:human/TRAPPC13/TRAPPC13-uniprot.txt A5PLN9; Q9UL33: TRAPPC2L; NbExp=3 file:human/TRAPPC13/TRAPPC13-uniprot.txt A5PLN9; O43617: TRAPPC3; NbExp=2 file:human/TRAPPC13/TRAPPC13-uniprot.txt A5PLN9; Q9Y2L5: TRAPPC8; NbExp=2 |
| GO:0005515 protein binding | IPI PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling... | MARK AS OVER ANNOTATED | Summary: Generic protein binding from a proteome-scale AP-MS map is not an informative TRAPPC13 molecular-function annotation. Reason: Mark as over-annotated. The BioPlex-style interactome evidence can support interaction context, but the more informative representation for TRAPPC13 is TRAPP complex membership and complex-level trafficking. Supporting Evidence: PMID:33961781 These networks model the interactome whose structure encodes protein function, localization, and complex membership file:human/TRAPPC13/TRAPPC13-uniprot.txt A5PLN9; Q9UL33: TRAPPC2L; NbExp=3 |
| GO:0005737 cytoplasm | NAS PMID:27066478 TRAPP Complexes in Secretion and Autophagy. | ACCEPT | Summary: Cytoplasm is a broad but reasonable location for TRAPPC13-containing TRAPP biology. Reason: Accept as broad supported cellular location/context. UniProt/ComplexPortal includes the cytoplasm row, and TRAPPC13 participates in cytosolic/peripheral TRAPP trafficking complexes. Supporting Evidence: file:human/TRAPPC13/TRAPPC13-uniprot.txt GO; GO:0005737; C:cytoplasm; NAS:ComplexPortal. Reactome:R-HSA-8877475 RAB1 nucleotide exchange is stimulated in these pathways by the GEF activity of the multisubunit TRAPPC complexes II and III |
| GO:0006888 endoplasmic reticulum to Golgi vesicle-mediated transport | NAS PMID:27066478 TRAPP Complexes in Secretion and Autophagy. | ACCEPT | Summary: TRAPPC13-containing TRAPP complex context supports ER-to-Golgi vesicle-mediated transport. Reason: Accept as the best supported process-level annotation. Reactome models TRAPPC complexes II and III as RAB1 GEFs in COPII-mediated ER-to-ERGIC/Golgi traffic, and UniProt/ComplexPortal carries the ER-to-Golgi transport row. The falcon deep research reinforces that TRAPPC13, via its TRAPPIII context, supports Rab1 activation in ER-to-Golgi vesicular transport (a complex-level role, not a TRAPPC13-autonomous activity). Supporting Evidence: Reactome:R-HSA-8877475 RAB1 is involved in COPII-mediated anterograde traffic from the endoplasmic reticulum to the ERGIC Reactome:R-HSA-8877475 RAB1 nucleotide exchange is stimulated in these pathways by the GEF activity of the multisubunit TRAPPC complexes II and III PMID:27066478 The mammalian Golgi TRAPP II (see above) was shown to act in vitro as a Rab1, but not Rab11, GEF file:human/TRAPPC13/TRAPPC13-uniprot.txt GO; GO:0006888; P:endoplasmic reticulum to Golgi vesicle-mediated transport; NAS:ComplexPortal. file:human/TRAPPC13/TRAPPC13-deep-research-falcon.md TRAPPC13, through its role in TRAPPIII, is essential for ER-to-Golgi vesicular transport |
| GO:0006901 vesicle coat assembly | NAS PMID:27066478 TRAPP Complexes in Secretion and Autophagy. | MODIFY | Summary: The coat-assembly annotation captures COPII-associated transport context but overstates TRAPPC13 as a coat assembly factor. Reason: Modify to ER-to-Golgi vesicle-mediated transport. The accessible evidence supports TRAPP complex recruitment/RAB1 exchange in COPII-associated early secretory traffic, not direct assembly of a vesicle coat by TRAPPC13. Proposed replacements: endoplasmic reticulum to Golgi vesicle-mediated transport Supporting Evidence: Reactome:R-HSA-8877475 RAB1 is involved in COPII-mediated anterograde traffic from the endoplasmic reticulum to the ERGIC Reactome:R-HSA-8877475 TRAPPCII is recruited to ER-derived vesicles by virtue of an interaction between the TRAPPCII component TRAPPC3 and the COPII coat protein SEC23 PMID:27066478 These findings provide information of TRAPP interactions with one membrane |
| GO:0099022 obsolete vesicle tethering | NAS PMID:27066478 TRAPP Complexes in Secretion and Autophagy. | MODIFY | Summary: The obsolete vesicle-tethering annotation should not be retained as-is. Reason: Modify to ER-to-Golgi vesicle-mediated transport, the supported TRAPPC13 TRAPP process. The term is obsolete and the review literature cautions that direct TRAPP membrane-tethering evidence remains inconclusive. Proposed replacements: endoplasmic reticulum to Golgi vesicle-mediated transport Supporting Evidence: PMID:27066478 evidence that any TRAPP complex acts as a membrane tether is currently inconclusive PMID:27066478 evidence for a direct role for TRAPP complexes in membrane tethering is lacking Reactome:R-HSA-8877475 RAB1 nucleotide exchange is stimulated in these pathways by the GEF activity of the multisubunit TRAPPC complexes II and III |
| GO:1990071 TRAPPII protein complex | NAS PMID:27066478 TRAPP Complexes in Secretion and Autophagy. | ACCEPT | Summary: TRAPPC13 is supportable as part of human TRAPPII complex context, especially from UniProt/ComplexPortal and Trs65/TRAPPII literature. Reason: Accept as supported complex membership/context. UniProt lists TRAPPII ComplexPortal membership for TRAPPC13, and TRAPPC13 is the human Trs65 homolog, a TRAPP II-specific subunit in yeast; mammalian assignments differ between TRAPPII and TRAPPIII sources, so both complex rows should be retained with this caveat. Supporting Evidence: file:human/TRAPPC13/TRAPPC13-uniprot.txt GO; GO:1990071; C:TRAPPII protein complex; NAS:ComplexPortal. file:human/TRAPPC13/TRAPPC13-uniprot.txt ComplexPortal; CPX-4749; TRAPP II complex, TRAPPC2 variant. file:human/TRAPPC13/TRAPPC13-uniprot.txt ComplexPortal; CPX-6902; TRAPP II complex, TRAPPC2B variant. PMID:27066478 Trs65 (560)TrappC13 (C5orf44) (417)Yeast TRAPP II assembly, dimer formation PMID:21453443 Trs65 and Tca17 interact with distinct domains of Trs130 |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8877475 | ACCEPT | Summary: Cytosol is consistent with TRAPPC13-containing TRAPP trafficking reactions. Reason: Accept as supported location/context for soluble/peripheral TRAPP complex biology. Supporting Evidence: file:human/TRAPPC13/TRAPPC13-uniprot.txt GO; GO:0005829; C:cytosol; TAS:Reactome. Reactome:R-HSA-8877475 RAB1 nucleotide exchange is stimulated in these pathways by the GEF activity of the multisubunit TRAPPC complexes II and III |
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Download this section (compressed HTML)Q: Should human TRAPPC13 be curated as TRAPPII, TRAPPIII, or both, given the difference between yeast Trs65/TRAPPII assignment, mammalian genetic-interaction TRAPPIII models, and ComplexPortal TRAPPII entries?
Suggested experts: ComplexPortal curators, Reactome TRAPP curators, GO transport editors
Q: Should TRAPPC13 generic protein-binding annotations be replaced by more informative TRAPP complex membership and complex-level Rab/RAB GEF annotations?
Suggested experts: GO molecular function editors, IntAct curators
Q: Is there direct experimental evidence for a TRAPPC13-specific autophagy or ATG9-trafficking annotation, or should PN autophagy context remain limited to TRAPPIII/TRAPP complex membership?
Suggested experts: GO autophagy editors, Reactome TRAPP curators
Experiment: Reconstitute human TRAPPC13-containing TRAPPII and TRAPPIII assemblies and measure RAB1 nucleotide exchange with and without TRAPPC13.
Hypothesis: TRAPPC13 contributes to complex-level RAB1 GEF activity through TRAPP complex assembly or stability rather than acting as an independent enzyme.
Type: complex reconstitution and RAB GEF assay
Experiment: Deplete and rescue TRAPPC13 in mammalian cells and compare ER-to-Golgi cargo transport, Golgi morphology, RAB1 activation, and TRAPP subunit integrity.
Hypothesis: TRAPPC13 supports early secretory trafficking by maintaining functional TRAPP complex architecture.
Type: trafficking rescue assay
Experiment: Test TRAPPC13 perturbation in ATG9 cycling, LC3/WIPI2 puncta formation, and starvation-induced autophagy alongside TRAPPC8-positive controls.
Hypothesis: If TRAPPC13 has a specific PN autophagy role, it should affect TRAPPIII-dependent ATG9/autophagosome initiation readouts beyond generic secretory pathway disruption.
Type: autophagy trafficking assay
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