endoplasmic reticulum lumen

GO:0005788 · Membrane organelle · Subcellular region · Proposed

The volume enclosed by the membranes of the endoplasmic reticulum. [GO:0005788]

Synonyms: ER lumen

Part of: endoplasmic reticulum (GO:0005783)

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

Taxonomic distribution

• NCBITaxon:4932 Saccharomyces cerevisiae — COMMON: Budding yeast has endoplasmic-reticulum unfolded-protein-response and ERAD pathways coupled to ER protein-folding quality control. [DOI:10.1016/s0092-8674(00)80835-1]

Canonical examples

• NCBITaxon:4932 Saccharomyces cerevisiae — Budding-yeast model for Sec61-dependent protein movement across or into the endoplasmic reticulum membrane that bounds the ER lumen. [DOI:10.1091/mbc.3.2.129]

Functions

• Sec61-dependent ER protein translocation — Sec61 translocons move substrate polypeptides across or into the endoplasmic reticulum membrane that separates the cytosol from the ER lumen.
  • GO:0005784 GO:0005784 identifies the Sec61 translocon complex as the heterotrimeric ER membrane channel that mediates cotranslational and posttranslational protein translocation.
  • DOI:10.1091/mbc.3.2.129 Stirling et al. 1992 analyzed Saccharomyces cerevisiae sec61 mutants with endoplasmic-reticulum protein-insertion defects.
• ER lumen protein quality control — The ER lumen is the enclosed compartment whose protein-folding state is monitored by the unfolded-protein-response and ER-associated-degradation pathways.
  • DOI:10.1016/s0092-8674(00)80835-1 Travers et al. 2000 linked yeast unfolded-protein response signaling with ER-associated degradation.

Mechanism graphs

ER lumen topology and Sec61 translocation (FUNCTION)

The endoplasmic reticulum lumen is the ER-internal volume enclosed by the ER membrane and bounded by Sec61 protein-translocation channels.

Discussions

• INTERPRETATION (RESOLVED): Keep the ER membrane and Sec61 translocon as bounding or membrane-embedded structures rather than as ER lumen components. GO:0005788 denotes the volume enclosed by ER membranes, whereas GO:0005789 denotes the ER-bounding lipid bilayer and GO:0005784 denotes a membrane-embedded translocon.

Evidence

• GO:0005788 Gene Ontology cellular-component term for endoplasmic reticulum lumen.
• GO:0043233 Gene Ontology cellular-component parent term for organelle lumen.
• GO:0005783 Gene Ontology cellular-component term for the containing endoplasmic reticulum.
• GO:0005789 Gene Ontology cellular-component term for the bounding endoplasmic reticulum membrane.
• GO:0005784 Gene Ontology cellular-component term for the Sec61 translocon complex.
• DOI:10.1091/mbc.3.2.129 Stirling et al. 1992, 'Protein translocation mutants defective in the insertion of integral membrane proteins into the endoplasmic reticulum', Molecular Biology of the Cell.
• DOI:10.1016/s0092-8674(00)80835-1 Travers et al. 2000, 'Functional and genomic analyses reveal an essential coordination between the unfolded protein response and ER-associated degradation', Cell.

Curation history

• 2026-09-15T05:26:20Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
• 2026-09-15T05:27:03Z codex · EXPANDED_RECORD — Added exact ER lumen synonymy, organelle-lumen parentage, endoplasmic-reticulum parthood, Saccharomyces scope, Sec61 and ER quality-control functions, GO/DOI evidence, a nonmechanistic ER-lumen topology graph, and a resolved boundary interpretation.
• 2026-09-15T05:35:15Z codex · REVIEW_FIX — Addressed issues #935 and #936 by narrowing the Saccharomyces note to UPR/ERAD quality control and rewording the Sec61 function and graph as protein translocation at the ER-lumen boundary.

Source: data/structures/membrane_organelle/endoplasmic_reticulum_lumen.yaml