axonemal A tubule inner sheath

GO:0160111 · Cytoskeleton · Multiprotein complex · Proposed

The microtubule-inner-protein network inside the lumen of the A tubule of the axonemal doublet microtubule. [GO:0160111]

Part of: axonemal microtubule doublet inner sheath (GO:0160110); A axonemal microtubule (GO:0097649)

Taxonomic distribution

NCBITaxon:3055 Chlamydomonas reinhardtii — COMMON: Chlamydomonas axonemal A tubules contain a luminal inner-sheath MIP network within native doublet microtubules. [DOI:10.1016/j.cell.2019.09.030]

NCBITaxon:3055 Chlamydomonas reinhardtii — Green-algal model whose A-tubule luminal MIP densities were resolved in decorated axonemal doublets. [DOI:10.1016/j.cell.2019.09.030]

A-tubule luminal stabilization — The axonemal A tubule inner sheath is a luminal MIP network that helps stabilize the A tubule of the axonemal doublet.
- GO:0160111 GO defines the axonemal A tubule inner sheath as a MIP network inside the A-tubule lumen that helps stabilize the A tubule.
- DOI:10.1016/j.cell.2019.09.030 Ma et al. 2019 resolved interconnected MIP densities inside native Chlamydomonas A tubules.

In Chlamydomonas axonemal doublets, the A-tubule inner sheath is the MIP network inside the A-tubule lumen and is part of the doublet inner sheath.

Subject	Predicate	Object	Evidence
axonemal A tubule inner sheath	is part of	axonemal microtubule doublet inner sheath	`GO:0160111` GO places the axonemal A tubule inner sheath within the axonemal microtubule doublet inner sheath.
axonemal A tubule inner sheath	occupies lumen of	A axonemal microtubule	`GO:0160111` GO defines the A-tubule inner sheath as a MIP network inside the A-tubule lumen.
axonemal A tubule inner sheath	stabilizes	A axonemal microtubule	`GO:0160111` GO defines the A-tubule inner sheath by its A-tubule-stabilizing function.

CURATION_TODO (OPEN): Resolve exact conserved A-tubule MIP family groundings, positions and copy numbers for the axonemal A tubule inner sheath. GO exactly identifies the A-tubule inner sheath, but this pass does not assign individual A-lumen MIP families, positions or copy numbers.

GO:0160111 Gene Ontology cellular-component term for the axonemal A tubule inner sheath.
GO:0160110 Gene Ontology places the axonemal A tubule inner sheath within the axonemal microtubule doublet inner sheath.
GO:0097649 Gene Ontology places the axonemal A tubule inner sheath inside the A axonemal microtubule.
DOI:10.1016/j.cell.2019.09.030 Ma et al. 2019, 'Structure of the Decorated Ciliary Doublet Microtubule', Cell.

2026-09-23T18:01:37Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-23T18:02:18Z codex · EXPANDED_RECORD — Added inner-sheath and A-tubule parthood, Chlamydomonas scope, GO and DOI evidence, a nonmechanistic A-tubule inner-sheath graph, and an A-tubule MIP-family TODO.