epiplastidial membrane

GO:7770040 · Membrane organelle · Membrane · Proposed

The outermost lipid bilayer surrounding complex plastids in organisms that acquired their plastids through secondary endosymbiosis. This membrane is derived from the host cell's endomembrane system and is continuous with the rough endoplasmic reticulum and the outer nuclear envelope. In some species, the cytoplasmic face may be studded with ribosomes. [GO:7770040]

Synonyms: cERM; chloroplast ER membrane; epiplastid rough ER; EpM; EPrER

Part of: plastid (GO:0009536)

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

Components

Component	Type	Part of / acts on	Grounding	Genes	Stoichiometry	Essential	Role
epiplastidial lipid bilayer	Lipid	part of	Reviewed label only (reviewed name; no accession asserted)			ESSENTIAL	Outermost host-endomembrane-derived lipid bilayer that surrounds the complex plastid and can be continuous with rough endoplasmic reticulum and the outer nuclear envelope. `GO:7770040` GO:7770040 defines the epiplastidial membrane as the outermost lipid bilayer around secondary complex plastids. `DOI:10.1016/j.protis.2016.04.001` Flori et al. 2016 analyzed the ultrastructure of the Phaeodactylum tricornutum periplastidial compartment.

Taxonomic distribution

NCBITaxon:2850 Phaeodactylum tricornutum — COMMON: The pennate diatom Phaeodactylum tricornutum contains a complex secondary plastid whose outer epiplastidial membrane encloses the periplastidial compartment. [DOI:10.1016/j.protis.2016.04.001]

Canonical examples

NCBITaxon:2850 Phaeodactylum tricornutum — Diatom model used for ultrastructural analysis of the periplastidial compartment and its surrounding complex-plastid membranes. [DOI:10.1016/j.protis.2016.04.001]

Functions

complex-plastid outer boundary — The epiplastidial membrane forms the host-derived outermost membrane of secondary complex plastids and separates the periplastidial compartment from the host endomembrane system.
- GO:7770040 The GO definition places the epiplastidial membrane as the outermost host-endomembrane-derived bilayer around complex plastids.
- DOI:10.1007/s10265-005-0214-6 Hashimoto 2005 reviewed the ultrastructure and division of secondary plastids.

Discussions

CURATION_TODO (OPEN): Resolve an exact source-neutral grounding for the lipid constituent of the epiplastidial membrane. The record is exactly grounded to GO:7770040, but no exact source-neutral lipid or lipid-bilayer CURIE was curated for the host-derived epiplastidial membrane matrix.
CURATION_TODO (OPEN): Keep the epiplastidial membrane distinct from the periplastidial membrane in future complex-plastid topology. GO:7770040 denotes the outermost complex-plastid membrane, whereas GO:7770041 denotes the second outermost membrane that borders the periplastidial compartment on its plastid side.

Evidence

GO:7770040 Gene Ontology cellular-component term for the epiplastidial membrane.
GO:0042170 Gene Ontology cellular-component parent term for plastid membrane.
GO:0009536 Gene Ontology cellular-component term for plastid.
DOI:10.1007/s10265-005-0214-6 Hashimoto 2005, The ultrastructural features and division of secondary plastids, Journal of Plant Research.
DOI:10.1016/j.protis.2016.04.001 Flori et al. 2016, Ultrastructure of the Periplastidial Compartment of the Diatom Phaeodactylum tricornutum, Protist.
DOI:10.1093/plcell/koae275 Gueguen et al. 2024, Monogalactosyldiacylglycerol synthase isoforms play diverse roles inside and outside the diatom plastid, The Plant Cell.

Curation history

2026-10-03T05:00:41Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-10-03T05:01:58Z codex · EXPANDED_RECORD — Added GO synonymy and plastid-membrane parentage, curated a reviewed-label-only epiplastidial lipid-bilayer constituent, added Phaeodactylum tricornutum scope, a complex-plastid boundary function, GO and DOI evidence, and open lipid-grounding and periplastidial-boundary discussions.

Source: data/structures/membrane_organelle/epiplastidial_membrane.yaml