thylakoid membrane
The pigmented photosynthetic membrane of cyanobacteria and chloroplasts, enriched in photosystems, cytochrome b6f, ATP synthase, plastoquinone and glycolipids, where light-driven electron transport builds the proton motive force for photosynthetic ATP synthesis. [GO:0042651]
Synonyms: TM
Has part: phycobilisome (GO:0030089)
Components
| Component | Type | Part of / acts on | Grounding | Genes | Stoichiometry | Essential | Role |
|---|---|---|---|---|---|---|---|
| thylakoid glycerolipid matrix | Lipid | part of | ESSENTIAL | Specialized galactolipid-, sulfolipid- and phosphatidylglycerol-rich bilayer into which photosynthetic electron-transport complexes are embedded.
| |||
| photosystem II | Protein complex | part of | GO:0009523 | ESSENTIAL | Membrane complex that oxidizes water, releases oxygen, and reduces plastoquinone at the start of the linear electron-transport chain.
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| plastoquinone pool | Small molecule | part of | ESSENTIAL | Lipid-soluble electron carrier that diffuses within the thylakoid membrane between PSII and cytochrome b6f.
| |||
| cytochrome b6f complex | Protein complex | part of | GO:0009512 | ESSENTIAL | Oxidizes plastoquinol and links electron flow to proton translocation across the thylakoid membrane.
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| photosystem I | Protein complex | part of | GO:0009522 | ESSENTIAL | Light-driven complex that accepts electrons downstream of cytochrome b6f and feeds ferredoxin reduction.
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| proton-transporting ATP synthase complex | Protein complex | part of | GO:0045259 | ESSENTIAL | Uses the trans-thylakoid proton motive force to synthesize ATP.
|
Taxonomic distribution
NCBITaxon:1117Cyanobacteriota — COMMON: Most cyanobacteria carry thylakoid membranes, while Gloeobacter-like lineages perform photosynthesis at the plasma membrane and lack thylakoids. [DOI:10.1146/annurev-cellbio-120823-022747]NCBITaxon:2763Rhodophyta — COMMON: Red algal chloroplasts retain thylakoid membranes descended from the cyanobacterial endosymbiont. [DOI:10.1146/annurev-cellbio-120823-022747]
Canonical examples
NCBITaxon:1148Synechocystis sp. PCC 6803 — Cyanobacterial model for native photosynthetic-complex organization and thylakoid membrane dynamics. [DOI:10.1016/j.molp.2017.09.019]
Functions
- photosynthetic electron transport chain
GO:0009767— Thylakoid membrane complexes move electrons from water through plastoquinone, cytochrome b6f and photosystem I, coupling light absorption to proton translocation and ATP synthesis.DOI:10.1146/annurev-cellbio-120823-022747Perez-Boerema et al. 2024 review thylakoid electron transport as the membrane process that converts light into chemical energy.
- photosynthetic ATP synthesis — The membrane separates the thylakoid lumen from the cytoplasm or stroma so proton accumulation can drive ATP synthase.
DOI:10.1146/annurev-cellbio-120823-022747Perez-Boerema et al. 2024 describe proton motive force generation across thylakoid membranes and ATP synthase use of that gradient.
Mechanism graphs
Linear electron transport builds a trans-thylakoid proton gradient (FUNCTION)
Photosystem II, plastoquinone, cytochrome b6f and photosystem I form an electron-transport chain in the thylakoid membrane. Electron flow is coupled to proton accumulation in the thylakoid lumen, and ATP synthase converts that proton motive force into ATP.
| Subject | Predicate | Object | Evidence |
|---|---|---|---|
| photosystem II | reduces | plastoquinone pool |
|
| plastoquinone pool | feeds electrons to | cytochrome b6f complex |
|
| cytochrome b6f complex | reduces the downstream carrier for | photosystem I |
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| cytochrome b6f complex | contributes to | trans-thylakoid proton motive force |
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| trans-thylakoid proton motive force | powers | proton-transporting ATP synthase complex |
|
| proton-transporting ATP synthase complex | carries out | photosynthetic ATP synthesis |
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Discussions
- CURATION_TODO (RESOLVED): Add separate PSI, PSII and cytochrome b6f records if the corpus needs the internal mechanisms of oxygen evolution, ferredoxin reduction or plastoquinol oxidation. They are multi-protein complexes and valid future CellStructureRecords, but the first thylakoid membrane record only needs them as grounded membrane components.
Evidence
DOI:10.1146/annurev-cellbio-120823-022747Perez-Boerema et al. 2024, Evolution of Thylakoid Structural Diversity, Annual Review of Cell and Developmental Biology.DOI:10.1016/j.molp.2017.09.019Casella et al. 2017, Dissecting the Native Architecture and Dynamics of Cyanobacterial Photosynthetic Machinery, Molecular Plant.DOI:10.1038/s41467-021-23680-1Huokko et al. 2021, Probing the biogenesis pathway and dynamics of thylakoid membranes, Nature Communications.
Curation history
2026-09-04T18:39:28Zclaude · CREATED_RECORD — Scaffolded by scripts/new_record.py2026-09-04T18:40:28Zclaude · EXPANDED_RECORD — Added thylakoid membrane components, taxonomy, examples, functions, evidence, a linear electron-transport graph, and a photosystem-splitting todo.2026-09-04T19:10:55Zclaude · FIXED_GROUNDING_LABEL — Aligned the ATP synthase causal node label with GO:0045259.2026-09-04T19:25:07Zclaude · FIXED_MEREOLOGY — Removed the overbroad GO:0045259 has_part link; kept ATP synthase as a grounded thylakoid component.2026-09-04T19:25:35Zclaude · FIXED_CAUSAL_GRAPH — Retargeted the ATP synthase edge to photosynthetic ATP synthesis instead of the upstream electron-transport process.2026-09-13T05:53:30Zcodex · RESOLVED_DISCUSSION — #756: marked the split_photosystem_records discussion resolved after the standalone PSI, PSII, and cytochrome b6f records were added.2026-09-20T21:55:39Zcodex · ADDRESSED_REVIEW — Retyped the photosystem II, cytochrome b6f, photosystem I, and ATP synthase graph nodes from GENE_OR_PROTEIN to STRUCTURE.
Source: data/structures/membrane_organelle/thylakoid_membrane.yaml