outer dynein arm

GO:0036157 · Cytoskeleton · Multiprotein complex · Proposed

An axonemal dynein complex that forms the outer dynein arm on ciliary and flagellar outer doublet microtubules and contains dynein heavy, intermediate and light chains. [GO:0036157]

Part of: axoneme (GO:0005930)

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

Components

Component	Type	Part of / acts on	Grounding	Essential	Role
outer-arm dynein heavy chains	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	UNKNOWN	Force-generating motor chains in the axonemal outer dynein arm. `GO:0036157` GO defines outer dynein arms as ciliary and flagellar outer-arm structures that contain two to three heavy chains. `DOI:10.1126/science.1128618` Nicastro et al. 2006 resolved dynein arms attached to Chlamydomonas outer doublet microtubules by cryoelectron tomography.
outer-arm dynein intermediate chains	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	UNKNOWN	Intermediate chains in the axonemal outer dynein arm protein complex. `GO:0036157` GO defines outer dynein arms as complexes that contain two or more intermediate chains.
outer-arm dynein light chains	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	UNKNOWN	Light-chain cohort of the axonemal outer dynein arm protein complex. `GO:0036157` GO defines outer dynein arms as complexes that contain a cluster of four to eight light chains.

Taxonomic distribution

NCBITaxon:3055 Chlamydomonas reinhardtii — COMMON: Chlamydomonas flagellar axonemes carry outer dynein arms that have been structurally characterized by cryoelectron tomography. [DOI:10.1126/science.1128618]

Canonical examples

NCBITaxon:3055 Chlamydomonas reinhardtii — Green-algal model whose demembranated flagellar axonemes show outer dynein arms attached to outer doublet microtubules. [DOI:10.1126/science.1128618]

Functions

microtubule sliding GO:0051012 — Outer dynein arms on Chlamydomonas axonemal doublets generate sliding forces that are converted into flagellar bends.
- DOI:10.1126/science.1128618 Nicastro et al. 2006 modeled how axonemal dynein arrangement on outer doublets can generate microtubule sliding forces.

Mechanism graphs

Outer dynein arms drive Chlamydomonas axonemal sliding (FUNCTION)

Outer-arm heavy, intermediate and light chains are constituents of an outer dynein arm that projects from Chlamydomonas axonemal outer doublet microtubules and contributes to sliding force generation.

Subject	Predicate	Object	Evidence
outer-arm dynein heavy chains	are part of	outer dynein arm	`GO:0036157` GO describes outer dynein arms as containing two to three dynein heavy chains.
outer-arm dynein intermediate chains	are part of	outer dynein arm	`GO:0036157` GO describes outer dynein arms as containing two or more intermediate chains.
outer-arm dynein light chains	are part of	outer dynein arm	`GO:0036157` GO describes outer dynein arms as containing a cluster of four to eight light chains.
outer dynein arm	projects from	outer doublet microtubules	`DOI:10.1126/science.1128618` Nicastro et al. 2006 resolved the arrangement of dynein arms on Chlamydomonas outer doublet microtubules.
outer dynein arm	drives	microtubule sliding	`GO:0036157` GO distinguishes inner and outer dynein arms as having different functions in microtubule-based motility. `DOI:10.1126/science.1128618` Nicastro et al. 2006 interpreted the axonemal dynein arrangement in a microtubule-sliding model.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral groundings for the outer-arm dynein heavy-chain, intermediate-chain and light-chain component classes. GO exactly identifies the outer dynein arm as a complex, but this curation pass did not verify exact InterPro, Pfam or other source-neutral accessions for the cross-taxon outer-arm chain classes.

Evidence

GO:0036157 Gene Ontology cellular-component term for the outer dynein arm.
GO:0005858 Gene Ontology places the outer dynein arm under the axonemal dynein complex.
GO:0005930 Gene Ontology cellular-component term for the axoneme.
DOI:10.1126/science.1128618 Nicastro et al. 2006, 'The molecular architecture of axonemes revealed by cryoelectron tomography', Science.

Curation history

2026-09-23T08:54:33Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-23T08:55:37Z codex · EXPANDED_RECORD — Added axonemal dynein parentage and axoneme parthood, Chlamydomonas scope, label-only outer-arm dynein chain components, microtubule-sliding function, GO and DOI evidence, a nonmechanistic outer-arm motility graph, and a component-grounding TODO.
2026-10-11T12:04:42Z codex · ADDRESS_SAVED_REVIEW — Addressed #2211: aligned the nonmechanistic dynein-arm graph with source-supported constituent parthood rather than assembly.

Source: data/structures/cytoskeleton/outer_dynein_arm.yaml