inner dynein arm

GO:0036156 · Cytoskeleton · Multiprotein complex · Proposed

An axonemal dynein complex that forms an inner dynein arm on ciliary and flagellar outer doublet microtubules. [GO:0036156]

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	Genes	Stoichiometry	Essential	Role
inner-arm dynein heavy chains	Protein	part of	Reviewed label only (reviewed name; no accession asserted)			UNKNOWN	Force-generating motor chains in axonemal inner dynein arms. `GO:0036156` GO defines inner dynein arms as ciliary and flagellar inner-arm structures that include multiple dynein heavy chains. `DOI:10.1126/science.1128618` Nicastro et al. 2006 resolved the arrangement of inner and outer dynein arms attached to Chlamydomonas axonemal outer doublets by cryoelectron tomography.

Taxonomic distribution

NCBITaxon:3055 Chlamydomonas reinhardtii — COMMON: Chlamydomonas flagellar axonemes carry inner 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 inner dynein arms attached to outer doublet microtubules. [DOI:10.1126/science.1128618]

Functions

microtubule sliding GO:0051012 — Inner 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 axonemal dynein organization on outer doublets as a basis for microtubule sliding forces.

Mechanism graphs

Inner dynein arms drive Chlamydomonas axonemal sliding (FUNCTION)

Inner-arm dynein heavy chains are motor-chain constituents of inner dynein arms that project from Chlamydomonas axonemal outer doublet microtubules and contribute to sliding force generation.

Subject	Predicate	Object	Evidence
inner-arm dynein heavy chains	are part of	inner dynein arm	`GO:0036156` GO describes inner dynein arms as containing a set of dynein heavy chains plus other subunits.
inner dynein arm	projects from	outer doublet microtubules	`GO:0036156` GO defines inner dynein arms as axonemal structures on ciliary and flagellar outer doublets. `DOI:10.1126/science.1128618` Nicastro et al. 2006 resolved the arrangement of dynein arms on Chlamydomonas outer doublet microtubules.
inner dynein arm	drives	microtubule sliding	`GO:0036156` 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 inner-arm dynein heavy-chain isoforms and accessory subunits. GO exactly identifies the inner dynein arm as a complex, but this curation pass did not verify exact InterPro, Pfam or other source-neutral accessions for the cross-taxon inner-arm chain classes or the Chlamydomonas heavy-chain isoforms.

Evidence

GO:0036156 Gene Ontology cellular-component term for the inner dynein arm.
GO:0005858 Gene Ontology places the inner dynein arm under the axonemal dynein complex.
GO:0005930 Gene Ontology places the inner dynein arm within the axoneme.
DOI:10.1126/science.1128618 Nicastro et al. 2006, 'The molecular architecture of axonemes revealed by cryoelectron tomography', Science.

Curation history

2026-09-23T10:45:33Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-23T10:46:20Z codex · EXPANDED_RECORD — Added axonemal dynein parentage and axoneme parthood, Chlamydomonas scope, a label-only inner-arm dynein heavy-chain component, microtubule-sliding function, GO and DOI evidence, a nonmechanistic inner-arm motility graph, and a component-grounding TODO.
2026-09-23T10:47:12Z codex · REFINE_INNER_DYNEIN_ARM_SCOPE — Corrected expansion-history wording to describe the single curated heavy-chain component and narrowed graph scope notes to avoid unsupported subcomplex classes.
2026-09-23T10:55:55Z codex · ADDRESSED_REVIEW — Resolved PR #1384 review issue #1385 by changing the inner-arm heavy-chain graph edge from assembly to static parthood.
2026-10-11T12:04:36Z codex · ADDRESS_SAVED_REVIEW — Addressed #2210: aligned the nonmechanistic dynein-arm graph with source-supported constituent parthood rather than assembly.

Source: data/structures/cytoskeleton/inner_dynein_arm.yaml