exomer complex

GO:0034044 · Other · Multiprotein complex · Proposed

A protein complex that acts as a selective cargo adaptor mediating the selective transport of specific membrane proteins from the trans-Golgi network (TGN) to the plasma membrane. [GO:0034044]

Synonyms: Chs5/6 complex

UniProt location names: UniProt Consortium, CC BY 4.0. Reference label and route sources.

Components

Component	Type	Part of / acts on	Grounding	Genes	Essential	Role
Chs5 exomer scaffold subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	CHS5	UNKNOWN	Scaffold subunit that assembles with Chs6-family ChAP cargo-binding subunits to form the yeast exomer complex. `GO:0034044` GO:0034044 defines the exomer complex as the cargo adaptor that mediates selected trans-Golgi-network-to-plasma-membrane transport. `DOI:10.1091/mbc.e06-03-0210` Sanchatjate and Schekman 2006 described Chs5, Chs6, Bch1, Bud7 and Bch2 in the yeast Chs5/6 exomer complex. `DOI:10.15252/embr.201540795` Huranova et al. 2016 showed that yeast exomer assembles at the trans-Golgi network by recruiting Chs5 before the ChAP cargo-binding subunits.
Chs6 exomer ChAP subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	CHS6	UNKNOWN	Chs5-Arf1-binding protein and cargo-binding subunit that helps select Chs3 for exomer-mediated export. `GO:0034044` GO:0034044 defines the exomer complex as the cargo adaptor that mediates selected trans-Golgi-network-to-plasma-membrane transport. `DOI:10.1091/mbc.e06-03-0210` Sanchatjate and Schekman 2006 described Chs5, Chs6, Bch1, Bud7 and Bch2 in the yeast Chs5/6 exomer complex. `DOI:10.1038/sj.emboj.7601007` Trautwein et al. 2006 named Chs6, Bch1, Bud7 and Bch2 as the ChAP family that interacts with Chs5 and Arf1 during specialized Golgi export.
Bch1 exomer ChAP subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	BCH1	UNKNOWN	Chs5-Arf1-binding protein that redundantly supports Chs3 association with Bud7 in the yeast exomer complex. `GO:0034044` GO:0034044 defines the exomer complex as the cargo adaptor that mediates selected trans-Golgi-network-to-plasma-membrane transport. `DOI:10.1091/mbc.e06-03-0210` Sanchatjate and Schekman 2006 described Chs5, Chs6, Bch1, Bud7 and Bch2 in the yeast Chs5/6 exomer complex. `DOI:10.1038/sj.emboj.7601007` Trautwein et al. 2006 named Chs6, Bch1, Bud7 and Bch2 as the ChAP family that interacts with Chs5 and Arf1 during specialized Golgi export.
Bud7 exomer ChAP subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	BUD7	UNKNOWN	Chs5-Arf1-binding protein that redundantly supports Chs3 association with Bch1 in the yeast exomer complex. `GO:0034044` GO:0034044 defines the exomer complex as the cargo adaptor that mediates selected trans-Golgi-network-to-plasma-membrane transport. `DOI:10.1091/mbc.e06-03-0210` Sanchatjate and Schekman 2006 described Chs5, Chs6, Bch1, Bud7 and Bch2 in the yeast Chs5/6 exomer complex. `DOI:10.1038/sj.emboj.7601007` Trautwein et al. 2006 named Chs6, Bch1, Bud7 and Bch2 as the ChAP family that interacts with Chs5 and Arf1 during specialized Golgi export.
Bch2 exomer ChAP subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	BCH2	UNKNOWN	Chs5-Arf1-binding protein represented among the ChAP cargo-binding subunits of yeast exomer. `GO:0034044` GO:0034044 defines the exomer complex as the cargo adaptor that mediates selected trans-Golgi-network-to-plasma-membrane transport. `DOI:10.1091/mbc.e06-03-0210` Sanchatjate and Schekman 2006 described Chs5, Chs6, Bch1, Bud7 and Bch2 in the yeast Chs5/6 exomer complex. `DOI:10.1038/sj.emboj.7601007` Trautwein et al. 2006 named Chs6, Bch1, Bud7 and Bch2 as the ChAP family that interacts with Chs5 and Arf1 during specialized Golgi export.

Taxonomic distribution

NCBITaxon:4932 Saccharomyces cerevisiae — COMMON: Budding yeast has a Chs5/ChAP exomer complex that mediates selected cargo export from the trans-Golgi network to the plasma membrane. [DOI:10.1083/jcb.200605106]

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — Budding-yeast model in which Chs5 and the ChAP subunits were assigned to the exomer cargo-adaptor complex. [DOI:10.1091/mbc.e06-03-0210]

Functions

Golgi to plasma membrane transport GO:0006893 — Exomer mediates selective export of specific membrane-protein cargoes from the trans-Golgi network to the plasma membrane.
- GO:0006893 GO:0006893 denotes vesicle-mediated transport from the trans-Golgi network to the plasma membrane.
- DOI:10.1083/jcb.200605106 Wang et al. 2006 named exomer as a yeast coat complex for select trans-Golgi-network-to-plasma-membrane transport.

Mechanism graphs

Chs5 and ChAP subunits assemble exomer for TGN export (ASSEMBLY)

In Saccharomyces cerevisiae, the Chs5 scaffold assembles with Chs6-family ChAP cargo-binding subunits to form exomer, which supports selected export from the trans-Golgi network to the plasma membrane.

Subject	Predicate	Object	Evidence
Arf1 GTPase	supports membrane recruitment of	exomer complex	`DOI:10.1038/sj.emboj.7601007` Trautwein et al. 2006 connected Arf1 with Chs5 and ChAP function in export of specialized Golgi cargo. `DOI:10.1083/jcb.200605106` Wang et al. 2006 described Arf1-dependent recruitment and membrane binding by the exomer coat complex.
Chs5 exomer scaffold subunit	assembles with	Chs6 exomer ChAP subunit	`DOI:10.15252/embr.201540795` Huranova et al. 2016 showed that yeast exomer assembles at the trans-Golgi network by recruiting Chs5 before the ChAP cargo-binding subunits.
Chs5 exomer scaffold subunit	assembles with	Bch1 exomer ChAP subunit	`DOI:10.15252/embr.201540795` Huranova et al. 2016 showed that yeast exomer assembles at the trans-Golgi network by recruiting Chs5 before the ChAP cargo-binding subunits.
Chs5 exomer scaffold subunit	assembles with	Bud7 exomer ChAP subunit	`DOI:10.15252/embr.201540795` Huranova et al. 2016 showed that yeast exomer assembles at the trans-Golgi network by recruiting Chs5 before the ChAP cargo-binding subunits.
Chs5 exomer scaffold subunit	assembles with	Bch2 exomer ChAP subunit	`DOI:10.15252/embr.201540795` Huranova et al. 2016 showed that yeast exomer assembles at the trans-Golgi network by recruiting Chs5 before the ChAP cargo-binding subunits.
Chs5 exomer scaffold subunit	localizes to	trans-Golgi network	`DOI:10.15252/embr.201540795` Huranova et al. 2016 showed that yeast exomer assembles at the trans-Golgi network by recruiting Chs5 before the ChAP cargo-binding subunits.
Chs5 exomer scaffold subunit	is part of	exomer complex	`DOI:10.1091/mbc.e06-03-0210` Sanchatjate and Schekman 2006 described Chs5, Chs6, Bch1, Bud7 and Bch2 in the yeast Chs5/6 exomer complex.
Chs6 exomer ChAP subunit	is part of	exomer complex	`DOI:10.1091/mbc.e06-03-0210` Sanchatjate and Schekman 2006 described Chs5, Chs6, Bch1, Bud7 and Bch2 in the yeast Chs5/6 exomer complex.
Bch1 exomer ChAP subunit	is part of	exomer complex	`DOI:10.1091/mbc.e06-03-0210` Sanchatjate and Schekman 2006 described Chs5, Chs6, Bch1, Bud7 and Bch2 in the yeast Chs5/6 exomer complex.
Bud7 exomer ChAP subunit	is part of	exomer complex	`DOI:10.1091/mbc.e06-03-0210` Sanchatjate and Schekman 2006 described Chs5, Chs6, Bch1, Bud7 and Bch2 in the yeast Chs5/6 exomer complex.
Bch2 exomer ChAP subunit	is part of	exomer complex	`DOI:10.1091/mbc.e06-03-0210` Sanchatjate and Schekman 2006 described Chs5, Chs6, Bch1, Bud7 and Bch2 in the yeast Chs5/6 exomer complex.
exomer complex	participates in	Golgi to plasma membrane transport	`DOI:10.1083/jcb.200605106` Wang et al. 2006 named exomer as the complex that transports select membrane proteins from the trans-Golgi network to the plasma membrane.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral InterPro, Pfam, or NCBIfam groundings for the five yeast exomer subunit classes. This first exomer record names the yeast Chs5, Chs6, Bch1, Bud7 and Bch2 constituent subunits but leaves InterPro, Pfam, or NCBIfam grounding unset until exact orthology and paralogy boundaries are reviewed per subunit.
CURATION_TODO (RESOLVED): Do not model Arf1 as a constituent exomer subunit. Arf1 binds ChAPs and supports exomer membrane association for Golgi export, but the curated exomer identity is the stable Chs5/ChAP cargo-adaptor complex rather than its recruiting Arf-family GTPase.

Evidence

GO:0034044 Gene Ontology cellular-component term for the exomer complex.
GO:0032991 Gene Ontology cellular-component parent term for protein-containing complexes.
GO:0006893 Gene Ontology biological-process term for Golgi-to-plasma-membrane transport.
DOI:10.1038/sj.emboj.7601007 Trautwein et al. 2006, Arf1p, Chs5p and the ChAPs are required for export of specialized cargo from the Golgi, The EMBO Journal.
DOI:10.1083/jcb.200605106 Wang, Hamamoto, Orci and Schekman 2006, Exomer: a coat complex for transport of select membrane proteins from the trans-Golgi network to the plasma membrane in yeast, Journal of Cell Biology.
DOI:10.1091/mbc.e06-03-0210 Sanchatjate and Schekman 2006, Chs5/6 complex: a multiprotein complex that interacts with and conveys chitin synthase III from the trans-Golgi network to the cell surface, Molecular Biology of the Cell.
DOI:10.15252/embr.201540795 Huranova, Muruganandam, Weiss and Spang 2016, Dynamic assembly of the exomer secretory vesicle cargo adaptor subunits, EMBO Reports.

Curation history

2026-09-18T07:32:14Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-18T07:33:22Z codex · EXPANDED_RECORD — Added exomer protein-complex parentage, the Chs5/6 synonym, reviewed-label-only yeast Chs5 and ChAP components, Saccharomyces scope, a Golgi-to-plasma-membrane transport function, GO/DOI evidence, a nonmechanistic exomer assembly graph, and subunit grounding plus Arf1-boundary discussions.
2026-09-18T07:33:55Z codex · REFORMATTED_RECORD — Expanded shared YAML evidence aliases into plain repeated mappings.
2026-09-18T07:47:07Z codex · FIXED_DISCUSSION_ANCHOR — Retargeted the Arf1 boundary discussion from the invalid whole components section to the five concrete exomer component anchors.
2026-09-18T07:57:56Z codex · REFINED_ARF1_EDGE — #1132: Retargeted the Arf1 graph edge from Chs5-specific recruitment to whole-exomer membrane recruitment and cited Wang et al. 2006 for the Arf1-dependent membrane-binding evidence.

Source: data/structures/other/exomer_complex.yaml