TRAPPIII protein complex
A complex that functions in anterograde transport at the Golgi and also regulates autophagy. In yeast it includes at least the following subunits: Bet3 (as homodimer), Bet5, Trs20, Trs23, Trs31, Trs33, Trs85. TRAPPIII may include further, as yet undescribed, proteins. [GO:1990072]
Components
| Component | Type | Part of / acts on | Grounding | Genes | Stoichiometry | Essential | Role |
|---|---|---|---|---|---|---|---|
| Bet3 TRAPPIII subunit | Protein | part of | Reviewed label only (reviewed name; no accession asserted) | BET3 | UNKNOWN | Shared TRAPP core constituent present as the homodimeric Bet3 subunit class in yeast TRAPPIII.
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| Bet5 TRAPPIII subunit | Protein | part of | Reviewed label only (reviewed name; no accession asserted) | BET5 | UNKNOWN | Shared TRAPP core constituent of the yeast TRAPPIII vesicle-tethering complex.
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| Trs20 TRAPPIII subunit | Protein | part of | Reviewed label only (reviewed name; no accession asserted) | TRS20 | UNKNOWN | Shared TRAPP core constituent of the yeast TRAPPIII vesicle-tethering complex.
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| Trs23 TRAPPIII subunit | Protein | part of | Reviewed label only (reviewed name; no accession asserted) | TRS23 | UNKNOWN | Shared TRAPP core constituent of the yeast TRAPPIII vesicle-tethering complex.
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| Trs31 TRAPPIII subunit | Protein | part of | Reviewed label only (reviewed name; no accession asserted) | TRS31 | UNKNOWN | Shared TRAPP core constituent of the yeast TRAPPIII vesicle-tethering complex.
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| Trs33 TRAPPIII subunit | Protein | part of | Reviewed label only (reviewed name; no accession asserted) | TRS33 | UNKNOWN | Shared TRAPP core constituent of the yeast TRAPPIII vesicle-tethering complex.
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| Trs85 TRAPPIII subunit | Protein | part of | Reviewed label only (reviewed name; no accession asserted) | TRS85 | UNKNOWN | TRAPPIII constituent that directs yeast Ypt1 guanine-nucleotide-exchange activity to the phagophore assembly site.
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Taxonomic distribution
NCBITaxon:4932Saccharomyces cerevisiae — COMMON: Budding yeast has a Trs85-containing TRAPPIII complex implicated in phagophore assembly-site targeting during autophagy. [DOI:10.1073/pnas.1000063107]
Canonical examples
NCBITaxon:4932Saccharomyces cerevisiae — Budding-yeast model in which Trs85 was shown to target TRAPPIII Ypt1 GEF activity to the phagophore assembly site. [DOI:10.1073/pnas.1000063107]
Functions
- macroautophagy
GO:0016236— TRAPPIII contributes to macroautophagy by targeting Ypt1 GEF activity to the phagophore assembly site during autophagosome formation.GO:0016236GO:0016236 defines macroautophagy as the autophagic process that proceeds through autophagosome formation.DOI:10.1073/pnas.1000063107Lynch-Day et al. 2010 described TRAPPIII as an autophagy-specific Ypt1 GEF and showed that Trs85 directs it to the phagophore assembly site.
Mechanism graphs
TRAPPIII supports yeast autophagy (FUNCTION)
In Saccharomyces cerevisiae, Trs85 associates with shared TRAPP core subunits to define a TRAPPIII complex that contributes to phagophore assembly-site targeting in macroautophagy.
| Subject | Predicate | Object | Evidence |
|---|---|---|---|
| Bet3 TRAPPIII subunit | is part of | TRAPPIII protein complex |
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| Bet5 TRAPPIII subunit | is part of | TRAPPIII protein complex |
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| Trs20 TRAPPIII subunit | is part of | TRAPPIII protein complex |
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| Trs23 TRAPPIII subunit | is part of | TRAPPIII protein complex |
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| Trs31 TRAPPIII subunit | is part of | TRAPPIII protein complex |
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| Trs33 TRAPPIII subunit | is part of | TRAPPIII protein complex |
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| Trs85 TRAPPIII subunit | is part of | TRAPPIII protein complex |
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| TRAPPIII protein complex | participates in | macroautophagy |
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Discussions
- CURATION_TODO (OPEN): Resolve exact source-neutral family groundings for the seven curated yeast TRAPPIII subunits. This first TRAPPIII record names the yeast Bet3, Bet5, Trs20, Trs23, Trs31, Trs33 and Trs85 constituent subunits but leaves InterPro, Pfam, or Complex Portal grounding unset until exact orthology and paralogy boundaries are reviewed per subunit.
Evidence
GO:1990072Gene Ontology cellular-component term for the TRAPPIII protein complex.GO:0030008Gene Ontology cellular-component parent term for TRAPP complexes.GO:0016236Gene Ontology biological-process term for macroautophagy.DOI:10.1078/S0171-9335(04)70009-6Sacher et al. 2000, Identification and characterization of five new subunits of TRAPP, European Journal of Cell Biology.DOI:10.1073/pnas.1000063107Lynch-Day et al. 2010, Trs85 directs a Ypt1 GEF, TRAPPIII, to the phagophore to promote autophagy, Proceedings of the National Academy of Sciences.
Curation history
2026-09-17T08:14:01Zcodex · CREATED_RECORD — Scaffolded by scripts/new_record.py2026-09-17T08:15:27Zcodex · EXPANDED_RECORD — Added TRAPPIII parentage, reviewed-label-only yeast components for the shared core and the Trs85 TRAPPIII subunit, Saccharomyces cerevisiae scope, a macroautophagy function, GO/DOI evidence, a nonmechanistic yeast TRAPPIII autophagy graph, and a subunit-grounding TODO.2026-09-17T08:16:09Zcodex · REFINED_RECORD — Narrowed Lynch-Day et al. 2010 evidence to the Trs85 TRAPPIII subunit and macroautophagy statements instead of attaching it to every shared-core row.2026-09-17T08:25:43Zcodex · ADDRESSED_PR_REVIEW — Resolved PR #1129 issue #1130 by replacing the Trs85 role phrase 'Trs85-containing TRAPPIII constituent' with narrower wording for the subunit's phagophore assembly-site targeting role.2026-09-17T08:26:33Zcodex · REFINED_RECORD — Tightened the PR #1129 issue #1130 Trs85 role fix so Trs85 directs Ypt1 guanine-nucleotide-exchange activity rather than a 'Trs85-containing' GEF activity.2026-09-17T08:33:22Zcodex · REFINED_RECORD — Clarified the PR #1129 issue #1130 curation-history wording so it no longer exposes the intermediate Trs85-containing GEF-activity phrase.