Isw1a complex

GO:0036436 · Other · Multiprotein complex · Proposed

An Isw1 complex that binds DNA and has nucleosome-stimulated ATPase activity. In S. cerevisiae, contains an Isw1p ATPase subunit in complex with Ioc3p. [GO:0036436]

Synonyms: ISW1a

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
Isw1 Isw1a ATPase subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	ISW1		UNKNOWN	ISWI-family ATPase constituent of the budding-yeast Isw1a chromatin-remodeling complex. `DOI:10.1128/MCB.23.1.80-91.2003` Vary et al. 2003 separated the budding-yeast Isw1a complex from Isw1b and identified Isw1p as the shared ATPase subunit.
Ioc3 Isw1a subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	IOC3		UNKNOWN	Ioc protein constituent specific to the budding-yeast Isw1a complex. `DOI:10.1128/MCB.23.1.80-91.2003` Vary et al. 2003 identified Ioc3p as the Isw1-associated protein that forms the Isw1a complex with Isw1p.

Taxonomic distribution

NCBITaxon:4932 Saccharomyces cerevisiae — COMMON: Budding yeast is the source organism in which Vary et al. separated Isw1a from the related Isw1b complex. [DOI:10.1128/MCB.23.1.80-91.2003]

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — Vary et al. 2003 purified Isw1p-associated complexes from Saccharomyces cerevisiae and resolved the two-subunit Isw1a complex. [DOI:10.1128/MCB.23.1.80-91.2003]

Functions

chromatin remodeling GO:0006338 — The Isw1a complex is an ATP-dependent chromatin-remodeling complex with nucleosome-stimulated ATPase activity.
- GO:0006338 GO:0006338 is the Gene Ontology biological-process term for chromatin remodeling.
- GO:0036436 GO:0036436 defines Isw1a as an Isw1 chromatin complex with nucleosome-stimulated ATPase activity.

Mechanism graphs

Isw1a carries yeast chromatin remodeling (FUNCTION)

In Saccharomyces cerevisiae, Isw1 and Ioc3 form the Isw1a chromatin-remodeling complex.

Subject	Predicate	Object	Evidence
Isw1 Isw1a ATPase subunit	contributes to	Isw1a complex	`DOI:10.1128/MCB.23.1.80-91.2003` Vary et al. 2003 identified Isw1p in the budding-yeast Isw1a complex.
Ioc3 Isw1a subunit	contributes to	Isw1a complex	`DOI:10.1128/MCB.23.1.80-91.2003` Vary et al. 2003 identified Ioc3p in the budding-yeast Isw1a complex.
Isw1a complex	enables	chromatin remodeling	`GO:0036436` GO:0036436 defines the Isw1a cellular component as an Isw1 chromatin complex with nucleosome-stimulated ATPase activity.

Discussions

CURATION_TODO (OPEN): Curate exact source-neutral InterPro, Pfam, NCBIfam or UniProt family groundings for the Isw1a ATPase and Ioc3 component classes when terms that denote those classes can be verified. The Isw1 ATPase is shared between Isw1a and Isw1b, so exact grounding should avoid broad ATPase and domain terms that do not denote this Isw1 subunit class.

Evidence

GO:0036436 Gene Ontology cellular-component term for the Isw1a complex.
GO:0016587 Gene Ontology cellular-component parent term for Isw1 complexes.
GO:0006338 Gene Ontology biological-process term for chromatin remodeling.
PMID:12482963 PubMed identifier for Vary et al. 2003, the Molecular and Cellular Biology paper that identified the separable budding-yeast Isw1a and Isw1b complexes.
DOI:10.1128/MCB.23.1.80-91.2003 DOI for Vary et al. 2003, 'Yeast Isw1p forms two separable complexes in vivo', verified through NCBI E-utilities.

Curation history

2026-09-27T01:54:13Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-27T01:54:57Z codex · EXPANDED_RECORD — Added ISW1a exact synonymy, Isw1-complex parentage, Isw1 and Ioc3 constituent rows, yeast scope, chromatin-remodeling function, GO/PubMed/DOI evidence, a nonmechanistic function graph, and a subunit-grounding TODO.

Source: data/structures/other/isw1a_complex.yaml