mitosome outer membrane

cellstructuremech:mitosome_outer_membrane · Membrane organelle · Membrane · Proposed

The outer membrane of a mitosome is the mitosomal membrane facing the cytoplasm. [uniprot.location:SL-0443 — Mitosome outer membrane]

Synonyms: mitosomal outer membrane; outer mitosomal membrane

Part of: mitosome envelope (cellstructuremech:mitosome_envelope)

Xrefs: uniprot.location:SL-0443 — Mitosome outer membrane

Components

Component	Type	Part of / acts on	Grounding	Genes	Stoichiometry	Essential	Role
mitosome outer lipid bilayer	Lipid	part of	Reviewed label only (reviewed name; no accession asserted)			ESSENTIAL	Cytoplasm-facing lipid bilayer that forms the outer boundary of the mitosome envelope. `uniprot.location:SL-0443` — Mitosome outer membrane UniProt SL-0443 identifies the mitosome outer membrane as the mitosomal membrane facing the cytoplasm.

NCBITaxon:2759 Eukaryota — RARE: Mitosome outer membranes occur in the patchy anaerobic or microaerophilic microbial eukaryotes that retain double-membrane mitochondrion-related mitosomes. [DOI:10.1111/jeu.12922]
NCBITaxon:5759 Entamoeba histolytica — COMMON: The Entamoeba mitochondrion-related mitosome was identified as a double-membrane organelle. [DOI:10.1046/j.1365-2958.1999.01414.x]

NCBITaxon:5759 Entamoeba histolytica — Amoebozoan parasite in which a double-membrane mitochondrion-related mitosome was initially described. [DOI:10.1046/j.1365-2958.1999.01414.x]

The mitosome outer membrane is the cytoplasm-facing lipid bilayer of the mitosome envelope and bounds the intermembrane space.

Subject	Predicate	Object	Evidence
mitosome outer membrane	is part of	mitosome envelope	`uniprot.location:SL-0438` — Mitosome envelope UniProt SL-0438 defines the mitosome envelope as comprising the inner and outer mitosomal membranes plus the intermembrane space.
mitosome outer membrane	faces	cytoplasm	`uniprot.location:SL-0443` — Mitosome outer membrane UniProt SL-0443 defines the mitosome outer membrane by its orientation toward the cytoplasm.
mitosome outer membrane	bounds	mitosome intermembrane space	`uniprot.location:SL-0440` — Mitosome intermembrane space UniProt SL-0440 defines the mitosome intermembrane space as the space between the inner and outer mitosomal membranes.

CURATION_TODO (OPEN): Resolve an exact source-neutral grounding for the lipid constituent of the mitosome outer membrane. UniProt SL-0443 identifies the whole mitosome outer membrane, but the lipid bilayer constituent is intentionally left as a reviewed-label-only component until an exact source-neutral membrane-constituent CURIE is curated.

uniprot.location:SL-0443 — Mitosome outer membrane UniProt Subcellular Location entry SL-0443 identifies the mitosome outer membrane, lists mitosomal outer membrane and outer mitosomal membrane as exact synonyms, and places it under the mitosome membrane location.
uniprot.location:SL-0438 — Mitosome envelope UniProt Subcellular Location entry SL-0438 identifies the mitosome envelope as including the outer mitosomal membrane.
uniprot.location:SL-0440 — Mitosome intermembrane space UniProt Subcellular Location entry SL-0440 identifies the mitosome intermembrane space as the space between inner and outer mitosomal membranes.
GO:0031090 Gene Ontology cellular-component parent term for organelle membrane.
GO:0005737 — cytoplasm Gene Ontology cellular-component term for the cytoplasm faced by the mitosome outer membrane.
DOI:10.1046/j.1365-2958.1999.01414.x Tovar et al. 1999, The mitosome, a novel organelle related to mitochondria in the amitochondrial parasite Entamoeba histolytica, Molecular Microbiology.
DOI:10.1111/jeu.12922 Tachezy 2022, Hydrogenosomes and mitosomes: Mitochondria of anaerobic eukaryotes, Journal of Eukaryotic Microbiology.

2026-09-13T19:39:56Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-13T19:40:41Z codex · EXPANDED_RECORD — Added UniProt SL mitosomal-outer-membrane synonyms and xref, organelle-membrane parentage, mitosome-envelope parthood, a reviewed-label-only lipid-bilayer component, rare anaerobic eukaryote and Entamoeba scope, UniProt/GO/DOI evidence, a nonmechanistic outer membrane topology graph, and a lipid-bilayer grounding TODO.
2026-09-13T19:59:51Z codex · GROUNDED_TOPOLOGY_NODE — Grounded the mitosome intermembrane space topology node to cellstructuremech:mitosome_intermembrane_space after the exact record was curated from UniProt SL-0440.