cyanelle envelope

GO:0033112 · Membrane organelle · Membrane · Proposed

The double lipid bilayer enclosing the cyanelle and separating its contents from the rest of the cytoplasm; includes the intermembrane space. [GO:0033112]

Part of: cyanelle (GO:0009842)

Has part: cyanelle inner membrane (GO:0036012); cyanelle outer membrane (GO:0036013); cyanelle intermembrane space (GO:0036014)

Xrefs: uniprot.location:SL-0479 — Cyanelle envelope

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

Components

Component	Type	Part of / acts on	Grounding	Essential	Role
cyanelle outer membrane	Lipid	part of	`GO:0036013`	UNKNOWN	Cytoplasm-facing lipid bilayer of the double cyanelle envelope. `GO:0036013` GO:0036013 defines the cyanelle outer membrane as the cytoplasm-facing lipid bilayer of the cyanelle envelope. `DOI:10.1074/jbc.M116.746131` Kojima et al. 2016 localized Cyanophora paradoxa outer-cyanelle-membrane proteins outside the cyanelle peptidoglycan layer.
cyanelle inner membrane	Lipid	part of	`GO:0036012`	UNKNOWN	Stroma-facing lipid bilayer of the double cyanelle envelope. `GO:0036012` GO:0036012 defines the cyanelle inner membrane as the lumen-facing lipid bilayer of the cyanelle envelope that also faces the cyanelle stroma.
cyanelle peptidoglycan layer	Peptidoglycan	part of	Reviewed label only (reviewed name; no accession asserted)	UNKNOWN	Vestigial peptidoglycan wall-like layer retained between the inner and outer membranes of the cyanelle envelope. `GO:0036014` GO:0036014 defines the cyanelle intermembrane space as the region between the envelope lipid bilayers and states that it includes the peptidoglycan layer. `uniprot.location:SL-0479` — Cyanelle envelope UniProt SL-0479 describes the cyanelle envelope as including a vestigial peptidoglycan layer. `DOI:10.1128/jb.178.2.332-339.1996` Pfanzagl et al. 1996 characterized the Cyanophora paradoxa cyanelle peptidoglycan.

Taxonomic distribution

NCBITaxon:38254 Glaucocystophyceae — COMMON: Glaucocystophyte algae including Glaucocystis, Cyanoptyche, and Cyanophora retain cyanelle peptidoglycan. [PMID:8955325]
NCBITaxon:2762 Cyanophora paradoxa — COMMON: Cyanophora paradoxa is a glaucophyte model whose cyanelle envelope contains inner and outer membranes separated by a peptidoglycan-bearing intermembrane space. [DOI:10.1128/jb.178.2.332-339.1996]

Canonical examples

NCBITaxon:2762 Cyanophora paradoxa — Model glaucophyte used for ultrastructural and biochemical studies of cyanelle envelope membranes and peptidoglycan. [DOI:10.1104/pp.71.2.409]

Mechanism graphs

Cyanelle envelope topology (FUNCTION)

The cyanelle envelope is a double plastid envelope made of cytoplasm-facing outer and stroma-facing inner membranes with a peptidoglycan-containing intermembrane space between them.

Subject	Predicate	Object	Evidence
cyanelle envelope	is part of	cyanelle	`GO:0009842` GO:0009842 defines the cyanelle as being surrounded by a double membrane with peptidoglycan in the intermembrane space. `uniprot.location:SL-0479` — Cyanelle envelope UniProt SL-0479 places the cyanelle envelope under the cyanelle subcellular location.
cyanelle outer membrane	is part of	cyanelle envelope	`GO:0036013` GO:0036013 defines the cyanelle outer membrane as the cytoplasm-facing lipid bilayer of the envelope.
cyanelle inner membrane	is part of	cyanelle envelope	`GO:0036012` GO:0036012 defines the cyanelle inner membrane as the cyanelle-envelope bilayer that also faces the cyanelle stroma.
cyanelle inner membrane	bounds	cyanelle stroma	`GO:0036012` GO:0036012 defines the cyanelle inner membrane as the cyanelle-envelope bilayer that also faces the cyanelle stroma. `GO:0034060` GO:0034060 identifies the cyanelle stroma as the space enclosed by the double membrane of a cyanelle.
cyanelle envelope	contains	cyanelle intermembrane space	`GO:0036014` GO:0036014 defines the cyanelle intermembrane space as the region between the inner and outer lipid bilayers of the envelope.
cyanelle peptidoglycan layer	resides in	cyanelle intermembrane space	`GO:0036014` GO:0036014 states that the cyanelle intermembrane space includes the peptidoglycan layer. `DOI:10.1128/jb.178.2.332-339.1996` Pfanzagl et al. 1996 biochemically characterized Cyanophora paradoxa cyanelle peptidoglycan.

Discussions

INTERPRETATION (RESOLVED): Keep the whole cyanelle envelope record separate from the generic GO:0033113 cyanelle membrane fallback term. GO:0033112 identifies the whole double envelope including the intermembrane space, whereas GO:0033113 identifies either envelope lipid bilayer when the exact inner or outer cyanelle membrane is unspecified.
CURATION_TODO (OPEN): Resolve an exact source-neutral grounding for the peptidoglycan layer in the cyanelle envelope. GO and UniProt place a vestigial peptidoglycan layer in the cyanelle intermembrane space, but the resolved authority terms identify the whole intermembrane space rather than a standalone cyanelle peptidoglycan sheet.

Evidence

GO:0033112 Gene Ontology cellular-component term for cyanelle envelope.
GO:0009526 Gene Ontology cellular-component term for plastid envelope.
GO:0009842 Gene Ontology cellular-component term for cyanelle.
GO:0033113 Gene Ontology cellular-component term for the generic cyanelle membrane parent of the exact inner and outer envelope membranes.
GO:0036012 Gene Ontology cellular-component term for cyanelle inner membrane.
GO:0036013 Gene Ontology cellular-component term for cyanelle outer membrane.
GO:0036014 Gene Ontology cellular-component term for the cyanelle intermembrane space.
GO:0034060 Gene Ontology cellular-component term for cyanelle stroma.
uniprot.location:SL-0479 — Cyanelle envelope UniProt Subcellular Location entry SL-0479 maps Cyanelle envelope to GO:0033112 and places it under cyanelle and plastid 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.
DOI:10.1074/jbc.M116.746131 Kojima, Muramoto and Kusano 2016, Outer Membrane Proteins Derived from Non-cyanobacterial Lineage Cover the Peptidoglycan of Cyanophora paradoxa Cyanelles and Serve as a Cyanelle Diffusion Channel, Journal of Biological Chemistry.
PMID:8955325 Pfanzagl et al. 1996, N-acetylputrescine as a characteristic constituent of cyanelle peptidoglycan in glaucocystophyte algae, Journal of Bacteriology.

Curation history

2026-09-12T20:01:28Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-12T20:02:33Z codex · EXPANDED_RECORD — Added plastid-envelope parentage, cyanelle parthood, exact inner and outer membrane parts, the GO-defined intermembrane-space part, a reviewed-label-only peptidoglycan layer, the UniProt SL-0479 xref, glaucophyte distribution, a nonmechanistic cyanelle-envelope topology graph, and membrane-scope and peptidoglycan-layer discussions.
2026-09-12T20:11:52Z codex · ADDRESS_REVIEW — Resolved #700 by adding GO:0034060 cyanelle stroma evidence plus a stroma node and inner-membrane boundary edge to the cyanelle envelope 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.

Source: data/structures/membrane_organelle/cyanelle_envelope.yaml