Sec62/Sec63 complex

GO:0031207 · Other · Multiprotein complex · Proposed

An endoplasmic-reticulum protein complex that supports posttranslational targeting of proteins to the ER and is represented in yeast by a Sec62p, Sec63p, Sec71p, and Sec72p tetramer. [GO:0031207]

Synonyms: ER protein translocation subcomplex; Sec62/63 complex; Sec63 complex

Part of: endoplasmic reticulum Sec complex (GO:0031205); endoplasmic reticulum membrane (GO:0005789)

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
Sec62 translocon subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	SEC62	ESSENTIAL	Membrane subunit of the Sec62/Sec63 tetramer that participates in signal-sequence recognition during posttranslational ER import. `GO:0031207` GO:0031207 defines the yeast Sec62/Sec63 complex as a tetramer containing Sec62p. `DOI:10.1002/yea.954` Willer et al. 2003 studied Sec62p and Sec63p as the two essential proteins of the yeast tetrameric Sec62/Sec63 complex.
Sec63 translocon subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	SEC63	ESSENTIAL	Core Sec62/Sec63 subunit that engages Sec62p at the cytosolic face and links posttranslational substrates to lumenal Kar2/BiP cycling. `GO:0031207` GO:0031207 defines the yeast Sec62/Sec63 complex as a tetramer containing Sec63p. `DOI:10.1002/yea.954` Willer et al. 2003 demonstrated a specific Sec62p-Sec63p interaction in the yeast ER Sec63 complex.
Sec71 translocon subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	SEC71, SEC66	UNKNOWN	Accessory subunit of the yeast Sec62/Sec63 tetramer within the ER posttranslational translocation machinery. `GO:0031207` GO:0031207 defines the yeast Sec62/Sec63 complex as a tetramer containing Sec71p. `DOI:10.1038/s41586-018-0856-x` Wu et al. 2019 structurally resolved Sec71/Sec66 with Sec62p, Sec63p, and Sec72p in the yeast post-translational ER translocation machinery.
Sec72 translocon subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	SEC72	UNKNOWN	Accessory subunit of the yeast Sec62/Sec63 tetramer that helps organize the cytosolic face of the complex. `GO:0031207` GO:0031207 defines the yeast Sec62/Sec63 complex as a tetramer containing Sec72p. `DOI:10.1002/yea.954` Willer et al. 2003 assayed Sec72p interactions at the cytosolic surface of the yeast Sec63 complex.

Taxonomic distribution

NCBITaxon:4932 Saccharomyces cerevisiae — COMMON: Budding yeast contains an ER-membrane Sec62/Sec63 tetramer with Sec62p, Sec63p, Sec71p, and Sec72p. [GO:0031207]

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — Yeast model in which the tetrameric Sec62/Sec63 complex was defined as part of the posttranslational ER import machinery. [DOI:10.1002/yea.954]

Functions

Sec62/Sec63-dependent posttranslational ER protein targeting — The Sec62/Sec63 complex cooperates with the Sec61 channel and Kar2/BiP machinery during SRP-independent posttranslational protein import into the endoplasmic reticulum.
- GO:0031207 GO:0031207 defines the Sec62/Sec63 complex by its involvement in posttranslational targeting of proteins to the ER.
- DOI:10.1091/mbc.e03-06-0390 Plath et al. 2004 photo-crosslinked prepro-alpha-factor to Sec62p and Sec61p in the yeast Sec complex during posttranslational ER import.
- DOI:10.1038/s41586-018-0856-x Wu et al. 2019 determined a structure of the yeast ER post-translational protein translocation machinery.

Mechanism graphs

Sec62/Sec63 organizes posttranslational ER import (FUNCTION)

The Sec62/Sec63 tetramer forms the ER Sec complex with the Sec61 channel and supports posttranslational protein import into the endoplasmic reticulum.

Subject	Predicate	Object	Evidence
Sec62 translocon subunit	is core subunit of	Sec62/Sec63 complex	`GO:0031207` GO:0031207 lists Sec62p in the yeast Sec62/Sec63 tetramer.
Sec63 translocon subunit	is core subunit of	Sec62/Sec63 complex	`DOI:10.1002/yea.954` Willer et al. 2003 identified a specific Sec62p-Sec63p interaction at the cytosolic surface of the Sec63 complex.
Sec71 translocon subunit	is accessory subunit of	Sec62/Sec63 complex	`GO:0031207` GO:0031207 lists Sec71p in the yeast Sec62/Sec63 tetramer.
Sec72 translocon subunit	is accessory subunit of	Sec62/Sec63 complex	`GO:0031207` GO:0031207 lists Sec72p in the yeast Sec62/Sec63 tetramer.
Sec62/Sec63 complex	is subcomplex of	endoplasmic reticulum Sec complex	`GO:0031205` GO:0031205 defines the yeast ER Sec complex as containing the Sec61 and Sec62/Sec63 subcomplexes.
Sec62/Sec63 complex	is embedded in	endoplasmic reticulum membrane	`DOI:10.1002/yea.954` Willer et al. 2003 studied the Sec63 complex in the yeast ER membrane.
Sec62/Sec63 complex	supports	Sec62/Sec63-dependent posttranslational ER protein targeting	`DOI:10.1091/mbc.e03-06-0390` Plath et al. 2004 showed that a posttranslational signal sequence contacts Sec62p and Sec61p in the yeast Sec complex. `DOI:10.1038/s41586-018-0856-x` Wu et al. 2019 resolved a yeast post-translational ER translocation assembly containing Sec61 and the Sec62/Sec63 subcomplex.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral groundings for Sec62, Sec63, Sec71/Sec66, and Sec72 before changing these component rows from reviewed labels to grounded families. GO exactly grounds the Sec62/Sec63 complex and its yeast Sec62p, Sec63p, Sec71p, and Sec72p constituents, but exact source-neutral family CURIEs were not curated in this pass.
INTERPRETATION (RESOLVED): Should Sec61-channel subunits or Kar2/BiP be included as Sec62/Sec63 complex components? GO:0031207 denotes the Sec62p/Sec63p/Sec71p/Sec72p subcomplex. The Sec61 heterotrimer combines with it in the broader ER Sec complex, and Kar2/BiP powers posttranslational import from the lumen, but neither is part of the Sec62/Sec63 tetramer.

Evidence

GO:0031207 Gene Ontology cellular-component term for the Sec62/Sec63 complex.
GO:0140534 Gene Ontology parent term for endoplasmic-reticulum protein-containing complexes.
GO:0031205 Gene Ontology cellular-component term for the broader endoplasmic reticulum Sec complex.
GO:0005789 Gene Ontology cellular-component term for the endoplasmic reticulum membrane.
DOI:10.1002/yea.954 Willer et al. 2003, Identification of novel protein-protein interactions at the cytosolic surface of the Sec63 complex in the yeast ER membrane, Yeast.
DOI:10.1091/mbc.e03-06-0390 Plath et al. 2004, Interactions between Sec complex and prepro-alpha-factor during posttranslational protein transport into the endoplasmic reticulum, Molecular Biology of the Cell.
DOI:10.1038/s41586-018-0856-x Wu, Cabanos and Rapoport 2019, Structure of the post-translational protein translocation machinery of the ER membrane, Nature.
DOI:10.1016/0092-8674(95)90077-2 Panzner et al. 1995, Posttranslational protein transport in yeast reconstituted with a purified complex of Sec proteins and Kar2p, Cell.

Curation history

2026-09-18T22:44:27Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-18T22:45:42Z codex · EXPANDED_RECORD — Added GO synonyms, ER-protein-complex parentage, Sec-complex and ER-membrane parthood, Sec62/Sec63/Sec71/Sec72 component rows, Saccharomyces scope, GO/DOI evidence, a mechanistic posttranslational ER import graph, and Sec62/Sec63 grounding and boundary discussions.
2026-09-18T22:55:50Z codex · ADDRESS_REVIEW — Resolved #1200 by adding the Sec63 complex literature synonym, resolved #1201 by changing Sec71 and Sec72 graph edges to accessory-subunit predicates, and resolved #1202 by adding the SEC66 alias to the Sec71 component.

Source: data/structures/other/sec62_sec63_complex.yaml