cyanelle intermembrane space

GO:0036014 · Membrane organelle · Subcellular region · Proposed

The region between the inner and outer lipid bilayers of the cyanelle envelope; includes the peptidoglycan layer. [GO:0036014]

Synonyms: cyanelle envelope lumen; cyanelle periplasm

Part of: cyanelle envelope (GO:0033112)

Xrefs: uniprot.location:SL-0481 — Cyanelle intermembrane space

Components

Component	Type	Part of / acts on	Grounding	Genes	Stoichiometry	Essential	Role
cyanelle peptidoglycan layer	Peptidoglycan	part of	Reviewed label only (reviewed name; no accession asserted)			UNKNOWN	Vestigial wall-like peptidoglycan layer retained in the intermembrane space between the inner and outer cyanelle envelope membranes. `GO:0036014` GO:0036014 defines the cyanelle intermembrane space as including the peptidoglycan layer. `uniprot.location:SL-0481` — Cyanelle intermembrane space UniProt SL-0481 describes the cyanelle intermembrane space as including the vestigial peptidoglycan layer. `DOI:10.1128/jb.178.2.332-339.1996` Pfanzagl et al. 1996 characterized Cyanophora paradoxa cyanelle peptidoglycan as a prokaryotic cell wall that is part of the organelle envelope.

NCBITaxon:38254 Glaucocystophyceae — COMMON: Glaucocystophyte algae including Glaucocystis, Cyanoptyche, and Cyanophora retain cyanelle peptidoglycan in the envelope compartment. [PMID:8955325]
NCBITaxon:2762 Cyanophora paradoxa — COMMON: Cyanophora paradoxa cyanelles retain peptidoglycan in the intermembrane space of the cyanelle envelope. [DOI:10.1128/jb.178.2.332-339.1996]

NCBITaxon:2762 Cyanophora paradoxa — Model glaucophyte used for biochemical characterization of cyanelle peptidoglycan retained in the organelle envelope. [DOI:10.1128/jb.178.2.332-339.1996]

The cyanelle intermembrane space lies between the inner and outer cyanelle envelope membranes and includes the cyanelle peptidoglycan layer.

Subject	Predicate	Object	Evidence
cyanelle outer membrane	delimits	cyanelle intermembrane space	`GO:0036014` GO:0036014 defines this space as the region between the inner and outer lipid bilayers of the cyanelle envelope. `GO:0036013` GO:0036013 defines the cyanelle outer membrane as the outer lipid bilayer of the envelope.
cyanelle inner membrane	delimits	cyanelle intermembrane space	`GO:0036014` GO:0036014 defines this space as the region between the inner and outer lipid bilayers of the cyanelle envelope. `GO:0036012` GO:0036012 defines the cyanelle inner membrane as the envelope bilayer that also faces the cyanelle stroma. `uniprot.location:SL-0480` — Cyanelle inner membrane UniProt SL-0480 describes the cyanelle inner membrane as separating the cyanelle stroma from the intermembrane space.
cyanelle peptidoglycan layer	resides in	cyanelle intermembrane space	`GO:0036014` GO:0036014 defines the cyanelle intermembrane space as including the peptidoglycan layer. `uniprot.location:SL-0481` — Cyanelle intermembrane space UniProt SL-0481 describes the cyanelle intermembrane space as including the vestigial peptidoglycan layer. `DOI:10.1128/jb.178.2.332-339.1996` Pfanzagl et al. 1996 biochemically characterized Cyanophora paradoxa cyanelle peptidoglycan.

CURATION_TODO (OPEN): Resolve an exact source-neutral grounding for the cyanelle peptidoglycan layer in the intermembrane space. GO:0036014 and UniProt SL-0481 support cyanelle peptidoglycan as a constituent of the cyanelle intermembrane space, but the curated authority terms identify the whole intermembrane space rather than a standalone cyanelle peptidoglycan layer.

GO:0036014 Gene Ontology cellular-component term for cyanelle intermembrane space.
GO:0009529 Gene Ontology cellular-component term for plastid intermembrane space.
GO:0033112 Gene Ontology cellular-component term for cyanelle envelope.
GO:0036012 Gene Ontology cellular-component term for cyanelle inner membrane.
uniprot.location:SL-0480 — Cyanelle inner membrane UniProt Subcellular Location entry SL-0480 maps Cyanelle inner membrane to GO:0036012 and describes it as the cyanelle membrane separating the cyanelle stroma from the intermembrane space.
GO:0036013 Gene Ontology cellular-component term for cyanelle outer membrane.
uniprot.location:SL-0481 — Cyanelle intermembrane space UniProt Subcellular Location entry SL-0481 maps Cyanelle intermembrane space to GO:0036014 and places it under plastid intermembrane space and the cyanelle envelope.
DOI:10.1104/pp.71.2.409 Giddings, Wasmann and Staehelin 1983, Structure of the Thylakoids and Envelope Membranes of the Cyanelles of Cyanophora paradoxa, Plant Physiology.
DOI:10.1128/jb.178.2.332-339.1996 Pfanzagl et al. 1996, Primary structure of cyanelle peptidoglycan of Cyanophora paradoxa: a prokaryotic cell wall as part of an organelle envelope, Journal of Bacteriology.
PMID:8955325 Pfanzagl et al. 1996, N-acetylputrescine as a characteristic constituent of cyanelle peptidoglycan in glaucocystophyte algae, Journal of Bacteriology.

2026-09-12T21:23:06Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-12T21:23:41Z codex · EXPANDED_RECORD — Changed the structure kind to subcellular region; added GO synonyms, plastid intermembrane-space parentage, cyanelle-envelope parthood, the UniProt SL-0481 xref, a reviewed-label-only peptidoglycan-layer component, glaucophyte distribution, a nonmechanistic envelope topology graph, and a peptidoglycan-layer grounding TODO.
2026-09-12T21:31:34Z codex · ADDRESS_REVIEW — Addressed #708 by adding UniProt SL-0480 record-level evidence and citing it on the inner-membrane boundary edge in the intermembrane-space topology graph.
2026-09-21T10:04:10Z codex · REPLACED_UNREADABLE_EVIDENCE — Replaced unreadable Jackson et al. 2015 Glaucophyta evidence with reachable cyanelle evidence for #1231.