mitosome inner membrane

cellstructuremech:mitosome_inner_membrane · Membrane organelle · Membrane · Proposed

The inner membrane of a mitosome is the membrane which separates the mitosomal matrix from the intermembrane space. [uniprot.location:SL-0439 — Mitosome inner membrane]

Synonyms: inner mitosomal membrane; mitosomal inner membrane

Part of: mitosome envelope (cellstructuremech:mitosome_envelope)

Xrefs: uniprot.location:SL-0439 — Mitosome inner membrane

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
mitosome inner lipid bilayer	Lipid	part of	Reviewed label only (reviewed name; no accession asserted)			ESSENTIAL	Matrix-facing lipid bilayer that separates the mitosomal matrix from the intermembrane space. `uniprot.location:SL-0439` — Mitosome inner membrane UniProt SL-0439 identifies the mitosome inner membrane as separating the mitosomal matrix from the intermembrane space.

Taxonomic distribution

NCBITaxon:2759 Eukaryota — RARE: Mitosome inner 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]

Canonical examples

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]

Mechanism graphs

Mitosome inner membrane topology (FUNCTION)

The mitosome inner membrane is the matrix-facing lipid bilayer that separates the mitosome matrix from the intermembrane space.

Subject	Predicate	Object	Evidence
mitosome inner 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 inner membrane	bounds	mitosome matrix	`uniprot.location:SL-0441` — Mitosome matrix UniProt SL-0441 defines the mitosome matrix as the internal spaces enclosed by the inner membrane.
mitosome inner membrane	delimits	mitosome intermembrane space	`uniprot.location:SL-0439` — Mitosome inner membrane UniProt SL-0439 defines the mitosome inner membrane by its position between the matrix and the 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.

Discussions

CURATION_TODO (OPEN): Resolve an exact source-neutral grounding for the lipid constituent of the mitosome inner membrane. UniProt SL-0439 identifies the whole mitosome inner 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.

Evidence

uniprot.location:SL-0439 — Mitosome inner membrane UniProt Subcellular Location entry SL-0439 identifies the mitosome inner membrane, lists inner mitosomal membrane and mitosomal inner 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 inner 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.
uniprot.location:SL-0441 — Mitosome matrix UniProt Subcellular Location entry SL-0441 identifies the mitosome matrix as the internal spaces enclosed by the mitosome inner membrane.
GO:0031090 Gene Ontology cellular-component parent term for organelle 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.

Curation history

2026-09-13T19:23:51Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-13T19:24:51Z codex · EXPANDED_RECORD — Added the UniProt SL mitosomal-inner-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 inner 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.
2026-09-13T20:16:06Z codex · GROUNDED_TOPOLOGY_NODE — Grounded the mitosome matrix topology node to cellstructuremech:mitosome_matrix after curating the exact UniProt SL-0441-backed record.

Source: data/structures/membrane_organelle/mitosome_inner_membrane.yaml