chloroplast envelope

GO:0009941 · Membrane organelle · Membrane · Proposed

The double lipid bilayer enclosing the chloroplast and separating its contents from the rest of the cytoplasm; includes the intermembrane space. [GO:0009941]

Part of: chloroplast (GO:0009507)

Has part: chloroplast outer membrane (GO:0009707); chloroplast inner membrane (GO:0009706); chloroplast intermembrane space (GO:0031972); Toc complex (GO:0010006); Tic complex (GO:0031897)

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

Components

Component	Type	Part of / acts on	Grounding	Essential	Role
chloroplast outer membrane	Lipid	part of	`GO:0009707`	UNKNOWN	Cytoplasm-facing lipid bilayer of the chloroplast envelope that carries the Toc outer-membrane translocon. `GO:0009707` GO:0009707 defines the chloroplast outer membrane as the cytoplasm-facing lipid bilayer of the chloroplast envelope.
chloroplast inner membrane	Lipid	part of	`GO:0009706`	UNKNOWN	Stroma-facing lipid bilayer of the chloroplast envelope that carries the Tic inner-envelope translocon. `GO:0009706` GO:0009706 defines the chloroplast inner membrane as the inner lipid bilayer of the chloroplast envelope facing the stroma.
Toc complex	Protein complex	part of	`GO:0010006`	UNKNOWN	Outer-envelope protein translocon that contributes the first chloroplast-envelope step for nuclear-encoded preprotein import. `GO:0010006` GO:0010006 defines the Toc complex as a protein translocon at the chloroplast outer membrane. `DOI:10.1016/j.cell.2022.10.030` Jin et al. 2022 resolved a Chlamydomonas TOC-TIC supercomplex that links the outer and inner chloroplast envelope translocons.
Tic complex	Protein complex	part of	`GO:0031897`	UNKNOWN	Inner-envelope translocon that facilitates chloroplast preprotein import across the inner envelope membrane. `GO:0031897` GO:0031897 defines the Tic complex as the translocon of the inner chloroplast envelope. `DOI:10.1016/j.cell.2022.10.030` Jin et al. 2022 resolved a Chlamydomonas TOC-TIC supercomplex that links the outer and inner chloroplast envelope translocons.

Taxonomic distribution

NCBITaxon:33090 Viridiplantae — COMMON: Photosynthetic green algae and land plants carry chloroplasts with envelopes inherited from primary plastids. [DOI:10.1098/rstb.2009.0103]
NCBITaxon:3055 Chlamydomonas reinhardtii — COMMON: The unicellular green alga Chlamydomonas reinhardtii has a chloroplast envelope with TOC-TIC import machinery. [DOI:10.1016/j.cell.2022.10.030]

Canonical examples

NCBITaxon:3055 Chlamydomonas reinhardtii — Green-algal model used for a resolved TOC-TIC supercomplex spanning two chloroplast envelope membranes. [DOI:10.1016/j.cell.2022.10.030]

Functions

protein import into chloroplast stroma GO:0045037 — Toc and Tic translocases route nuclear-encoded preproteins across the two chloroplast envelope membranes toward the stroma.
- GO:0045037 GO:0045037 defines protein import into the chloroplast stroma.
- DOI:10.1016/j.cell.2022.10.030 Jin et al. 2022 resolved a Chlamydomonas TOC-TIC supercomplex spanning both chloroplast envelope membranes.

Mechanism graphs

Chloroplast envelope routes stromal protein import (FUNCTION)

In Chlamydomonas, outer and inner chloroplast envelope membranes bound the intermembrane space while Toc and Tic translocons route nuclear-encoded preproteins toward the stroma.

Subject	Predicate	Object	Evidence
chloroplast envelope	encloses	chloroplast	`GO:0009941` GO:0009941 defines the chloroplast envelope as the double lipid bilayer enclosing the chloroplast.
chloroplast outer membrane	is part of	chloroplast envelope	`GO:0009707` GO:0009707 places the chloroplast outer membrane in the chloroplast envelope.
chloroplast inner membrane	is part of	chloroplast envelope	`GO:0009706` GO:0009706 places the chloroplast inner membrane in the chloroplast envelope.
chloroplast envelope	contains	chloroplast intermembrane space	`GO:0031972` GO:0031972 defines the chloroplast intermembrane space as the region between the inner and outer lipid bilayers of a chloroplast envelope.
chloroplast envelope	bounds	chloroplast stroma	`GO:0009570` GO:0009570 defines the chloroplast stroma as the space enclosed by the double membrane of a chloroplast, excluding the thylakoid space.
Toc complex	is part of	chloroplast outer membrane	`GO:0010006` GO:0010006 defines the Toc complex as a protein translocon at the chloroplast outer membrane.
Tic complex	is part of	chloroplast inner membrane	`GO:0031897` GO:0031897 defines the Tic complex as the translocon of the inner chloroplast envelope.
Toc complex	couples with	Tic complex	`DOI:10.1016/j.cell.2022.10.030` Jin et al. 2022 resolved a Chlamydomonas TOC-TIC supercomplex spanning the two chloroplast envelope membranes.
Toc complex	routes precursors toward	protein import into chloroplast stroma	`DOI:10.1016/j.cell.2022.10.030` Jin et al. 2022 resolved an outer-envelope Toc portion in a chloroplast protein-import supercomplex.
Tic complex	routes precursors toward	protein import into chloroplast stroma	`DOI:10.1016/j.cell.2022.10.030` Jin et al. 2022 resolved an inner-envelope Tic portion in a chloroplast protein-import supercomplex.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral records or component boundaries for envelope-spanning TOC-TIC supercomplexes, the Chlamydomonas YlmG-containing import module, and plastid protein-import ATPase subcomplexes. This first chloroplast envelope record grounds the separate Toc and Tic translocons exactly while avoiding a broader aggregate for every import factor embedded in, spanning, or peripherally associated with the envelope.

Evidence

GO:0009941 Gene Ontology cellular-component term for chloroplast envelope.
GO:0009526 Gene Ontology cellular-component term for plastid envelope.
GO:0009507 Gene Ontology cellular-component term for chloroplast.
GO:0009707 Gene Ontology cellular-component term for chloroplast outer membrane.
GO:0009706 Gene Ontology cellular-component term for chloroplast inner membrane.
GO:0031972 Gene Ontology cellular-component term for chloroplast intermembrane space.
GO:0009570 Gene Ontology cellular-component term for chloroplast stroma.
GO:0010006 Gene Ontology cellular-component term for the Toc complex.
GO:0031897 Gene Ontology cellular-component term for the Tic complex.
GO:0045037 Gene Ontology biological-process term for protein import into the chloroplast stroma.
DOI:10.1098/rstb.2009.0103 Keeling 2010, 'The endosymbiotic origin, diversification and fate of plastids', Philosophical Transactions of the Royal Society B.
DOI:10.1016/j.cell.2022.10.030 Jin et al. 2022, 'Structure of a TOC-TIC supercomplex spanning two chloroplast envelope membranes', Cell.

Curation history

2026-09-12T06:09:52Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-12T06:10:51Z codex · EXPANDED_RECORD — Added plastid-envelope parentage, chloroplast parthood, exact outer and inner membrane, intermembrane-space, Toc, and Tic parts, Viridiplantae and Chlamydomonas scope, stromal protein-import function, DOI/GO evidence, a nonmechanistic envelope-import graph, and an import-complex boundary TODO.
2026-09-12T06:17:49Z codex · REVIEW_FIXES — Resolved PR #596 review issues #597 and #598 by compacting precommit curation-history self-corrections and adding a GO:0009570 chloroplast stroma node plus envelope-boundary graph edge.
2026-09-20T21:55:39Z codex · ADDRESSED_REVIEW — Retyped the chloroplast Toc and Tic graph nodes as STRUCTURE.

Source: data/structures/membrane_organelle/chloroplast_envelope.yaml