EMC complex

GO:0072546 · Other · Multiprotein complex · Proposed

A transmembrane protein complex in the endoplasmic reticulum membrane that promotes insertion of newly synthesized proteins into the ER membrane. [GO:0072546]

Synonyms: endoplasmic reticulum membrane protein complex; ER membrane protein complex

Part of: endoplasmic reticulum membrane (GO:0005789)

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

Taxonomic distribution

NCBITaxon:4932 Saccharomyces cerevisiae — COMMON: Budding yeast contains an ER-membrane EMC complex; Bai et al. determined a Saccharomyces cerevisiae cryo-EM structure and reported eight EMC subunits. [DOI:10.1038/s41586-020-2389-3]

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — Budding-yeast model in which cryo-EM resolved the EMC transmembrane-domain insertase architecture. [DOI:10.1038/s41586-020-2389-3]

Functions

protein insertion into ER membrane GO:0045048 — EMC promotes insertion and correct topogenesis of selected tail-anchored and multipass transmembrane domains in the ER membrane.
- GO:0045048 GO:0045048 denotes incorporation of a protein into the endoplasmic-reticulum membrane with proper topogenic orientation.
- DOI:10.1126/science.aao3099 Guna et al. 2018 showed that purified EMC catalyzes transmembrane-domain insertion of eligible substrates in a reconstituted liposome system.
- DOI:10.1016/j.cell.2018.10.009 Chitwood et al. 2018 found that EMC initiates cotranslational insertion of the first transmembrane domain of tested GPCR substrates and cooperates with Sec61 for later transmembrane-domain insertion.

Mechanism graphs

EMC inserts transmembrane domains into the ER membrane (FUNCTION)

EMC is embedded in the endoplasmic-reticulum membrane, directly inserts selected transmembrane domains, and can cooperate with the Sec61 translocon during cotranslational topogenesis.

Subject	Predicate	Object	Evidence
EMC complex	is embedded in	endoplasmic reticulum membrane	`GO:0072546` GO:0072546 defines EMC as a transmembrane protein complex located in the endoplasmic reticulum. `DOI:10.1038/s41586-020-2389-3` Bai et al. 2020 determined the structure of Saccharomyces cerevisiae EMC and described the transmembrane subunits that form the membrane region.
EMC complex	supports	EMC-dependent ER transmembrane-domain insertion	`DOI:10.1126/science.aao3099` Guna et al. 2018 reconstituted EMC-dependent substrate insertion with purified EMC in synthetic liposomes. `DOI:10.7554/eLife.57887` O'Donnell et al. 2020 resolved human EMC architecture that suggested a path for energy-independent membrane insertion of transmembrane domains.
EMC complex	cooperates with	Sec61 translocon complex	`DOI:10.1016/j.cell.2018.10.009` Chitwood et al. 2018 found that purified EMC and SRP receptor were sufficient for correctly oriented first-transmembrane-domain insertion for beta1-adrenergic receptor, whereas Sec61 was required for insertion of the next transmembrane domain.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral component groundings and species-specific subunit boundaries for EMC before adding component rows. GO exactly grounds the EMC complex and carries older Saccharomyces subunit text, but Bai et al. report an eight-subunit Saccharomyces cerevisiae EMC. This record leaves individual Emc1, Emc2, Emc3/Kre27, Emc4, Emc5/Aim27, Emc6, Emc7 and Emc10 rows unasserted until exact family groundings and core or accessory status are curated.

Evidence

GO:0072546 Gene Ontology cellular-component term for the EMC complex.
GO:0098796 Gene Ontology cellular-component parent term for membrane protein complexes.
GO:0005789 Gene Ontology cellular-component term for the endoplasmic reticulum membrane.
GO:0005784 Gene Ontology cellular-component term for the Sec61 translocon complex.
GO:0045048 Gene Ontology biological-process term for protein insertion into ER membrane.
DOI:10.1126/science.aao3099 Guna, Volkmar, Christianson and Hegde 2018, The ER membrane protein complex is a transmembrane domain insertase, Science.
DOI:10.1016/j.cell.2018.10.009 Chitwood, Juszkiewicz, Guna, Shao and Hegde 2018, EMC Is Required to Initiate Accurate Membrane Protein Topogenesis, Cell.
DOI:10.7554/eLife.57887 O'Donnell et al. 2020, The architecture of EMC reveals a path for membrane protein insertion, eLife.
DOI:10.1038/s41586-020-2389-3 Bai, You, Feng, Kovach and Li 2020, Structure of the ER membrane complex, a transmembrane-domain insertase, Nature.

Curation history

2026-09-18T16:25:54Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-18T16:26:47Z codex · EXPANDED_RECORD — Added broad GO synonymy, membrane-complex parentage, ER-membrane parthood, Saccharomyces scope, an EMC-dependent membrane-insertion function, GO/DOI evidence, a nonmechanistic ER transmembrane-domain insertion graph, and an EMC subunit-boundary TODO.
2026-09-18T16:39:54Z codex · ADDRESS_REVIEW — Resolved #1167 by narrowing the insertion graph edge, resolved #1168 by adding top-level Sec61 GO evidence, and resolved #1169 by pairing Emc3/Kre27 and Emc5/Aim27 aliases in the subunit-boundary TODO.
2026-09-18T16:43:43Z codex · FIX_VALIDATION — Removed GO:0045048 from the narrowed graph-local EMC-dependent insertion node so its specific label does not misrepresent the broad GO process; kept GO:0045048 on the top-level exact process function.

Source: data/structures/other/emc_complex.yaml