LH2 peripheral light-harvesting antenna complex

cellstructuremech:lh2_peripheral_light_harvesting_antenna_complex · Energy complex · Multiprotein complex · Proposed

A peripheral bacteriochlorophyll-containing light-harvesting antenna protein complex of purple bacterial chromatophore membranes that broadens the photosynthetic absorption cross-section and transfers excitation energy toward RC-LH1 reaction-center core complexes. [DOI:10.1038/nature02823]

Synonyms: LH2 antenna complex; peripheral light-harvesting complex 2

Part of: plasma membrane-derived chromatophore membrane (GO:0042717)

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

Taxonomic distribution

NCBITaxon:2 Bacteria — RARE: LH2 antenna complexes occur in the chromatophore photosynthetic membranes of purple bacteria rather than broadly across bacteria. [uniprot.location:SL-0042 — Cellular chromatophore membrane]

Canonical examples

NCBITaxon:1063 Cereibacter sphaeroides — Purple photosynthetic bacterium, still commonly cited under the synonym Rhodobacter sphaeroides, whose native chromatophore membranes were imaged with LH2 complexes surrounding RC-LH1-PufX core arrays. [DOI:10.1038/nature02823]

Functions

photosynthesis, light harvesting GO:0009765 — The peripheral LH2 antenna broadens bacteriochlorophyll light capture and transfers excitation energy inward toward reaction-center LH1 core complexes.
- DOI:10.1038/nature02823 Bahatyrova et al. 2004 resolved LH2 antenna complexes around RC-LH1-PufX core arrays in native Rhodobacter sphaeroides photosynthetic membranes.
- uniprot.location:SL-0042 — Cellular chromatophore membrane UniProt SL-0042 lists antenna complexes among the contents of cellular chromatophore membranes.

Mechanism graphs

LH2 antennae feed purple-bacterial reaction-center cores (FUNCTION)

LH2 antenna complexes reside in the plasma membrane-derived chromatophore membrane and transfer captured excitation energy toward RC-LH1-PufX reaction-center core complexes.

Subject	Predicate	Object	Evidence
LH2 peripheral light-harvesting antenna complex	is part of	plasma membrane-derived chromatophore membrane	`uniprot.location:SL-0042` — Cellular chromatophore membrane UniProt SL-0042 lists antenna complexes among the contents of cellular chromatophore membranes. `DOI:10.1038/nature02823` Bahatyrova et al. 2004 imaged LH2 complexes in native Rhodobacter sphaeroides photosynthetic membranes.
LH2 peripheral light-harvesting antenna complex	transfers excitation energy to	RC-LH1-PufX core complex	`DOI:10.1038/nature02823` Bahatyrova et al. 2004 resolved LH2 complexes interconnecting and clustering around RC-LH1-PufX core arrays in native Rhodobacter sphaeroides photosynthetic membranes.
LH2 peripheral light-harvesting antenna complex	contributes to	photosynthesis, light harvesting	`DOI:10.1038/nature02823` Bahatyrova et al. 2004 describe LH2 as a peripheral antenna complex in the native Rhodobacter photosynthetic membrane.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral component groundings for LH2 alpha and beta apoprotein families and bacteriochlorophyll cofactor boundaries before adding component rows. The first LH2 record grounds the complex itself at a minted CellStructureMech identifier under GO:0030076, but it does not guess whether available protein-family terms exactly match the full purple-bacterial LH2 subunit families.

Evidence

GO:0030076 Gene Ontology cellular-component term for the broader light-harvesting complex class.
GO:0042717 Gene Ontology cellular-component term for the plasma membrane-derived chromatophore membrane that houses purple bacterial LH2 antenna complexes.
GO:0009765 Gene Ontology biological-process term for photosynthesis, light harvesting.
uniprot.location:SL-0042 — Cellular chromatophore membrane UniProt Subcellular Location entry for the cellular chromatophore membrane; maps to GO:0042717 and lists antenna complexes among the membrane contents.
DOI:10.1038/nature02823 Bahatyrova et al. 2004, The native architecture of a photosynthetic membrane, Nature.

Curation history

2026-09-13T06:10:36Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-13T06:11:10Z codex · EXPANDED_RECORD — Added LH2 synonymy, light-harvesting-complex parentage, chromatophore parthood, purple-bacterial scope, a Cereibacter example, photosynthetic light-harvesting function, GO/UniProt/literature evidence, a nonmechanistic LH2 excitation-transfer graph, and an LH2 subunit-boundary TODO.
2026-09-13T06:22:20Z codex · ADDRESS_REVIEW — #758: grounded the LH2 light-harvesting function and graph endpoint to GO:0009765.

Source: data/structures/energy_complex/lh2_peripheral_light_harvesting_antenna_complex.yaml