CHRAC

GO:0008623 · Other · Multiprotein complex · Proposed

An ISWI complex that contains an ATPase subunit of the ISWI family (SNF2H in mammals, Isw2 in S. cerevisiae), an ACF1 homolog, and additional small histone fold subunits (generally two of these, but Xenopus has only one and some additional non-conserved subunits). CHRAC plays roles in the regulation of RNA polymerase II transcription and in DNA replication and repair. [GO:0008623]

Synonyms: chromatin accessibility complex; ISW2 complex

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

Components

Component	Type	Part of / acts on	Grounding	Genes	Essential	Role
Isw2 CHRAC ATPase subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	ISW2	UNKNOWN	ISWI-family ATPase constituent of the budding-yeast CHRAC-like four-subunit Isw2 chromatin-remodeling complex. `DOI:10.1128/MCB.24.7.2605-2613.2004` McConnell et al. 2004 purified a four-subunit Isw2 complex containing Itc1p, Isw2p, Dpb4p, and Dls1p from Saccharomyces cerevisiae.
Itc1 CHRAC ACF1-homolog subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	ITC1	UNKNOWN	ACF1-homolog constituent paired with Isw2 in the budding-yeast CHRAC-like four-subunit Isw2 chromatin-remodeling complex. `DOI:10.1128/MCB.24.7.2605-2613.2004` McConnell et al. 2004 found Itc1p in the Dls1p-purified four-subunit Isw2 complex.
Dpb4 CHRAC histone-fold subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	DPB4	UNKNOWN	Small histone-fold constituent of the budding-yeast CHRAC-like four-subunit Isw2 complex. `DOI:10.1128/MCB.24.7.2605-2613.2004` McConnell et al. 2004 identified Dpb4p as a histone-fold subunit in the four-subunit Saccharomyces cerevisiae Isw2 complex. `DOI:10.1128/MCB.24.1.217-227.2004` Iida and Araki 2004 described Dpb4p in the putative budding-yeast ISW2/yCHRAC complex.
Dls1 CHRAC histone-fold subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	DLS1	UNKNOWN	Small histone-fold constituent of the budding-yeast CHRAC-like four-subunit Isw2 complex. `DOI:10.1128/MCB.24.7.2605-2613.2004` McConnell et al. 2004 identified Yjl065cp, named Dls1p, as a histone-fold subunit in the four-subunit Saccharomyces cerevisiae Isw2 complex. `DOI:10.1128/MCB.24.1.217-227.2004` Iida and Araki 2004 described Dls1p in the putative budding-yeast ISW2/yCHRAC complex.

Taxonomic distribution

NCBITaxon:4932 Saccharomyces cerevisiae — COMMON: Budding yeast is the source organism in which Iida and Araki described a putative ISW2/yCHRAC complex with Isw2, Itc1, Dpb4, and Dls1. [DOI:10.1128/MCB.24.1.217-227.2004]

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — McConnell et al. 2004 purified Dls1p-associated complexes from Saccharomyces cerevisiae and found a four-subunit Isw2 complex containing Itc1p, Isw2p, Dpb4p, and Dls1p. [DOI:10.1128/MCB.24.7.2605-2613.2004]

Functions

chromatin remodeling GO:0006338 — The CHRAC-like four-subunit Isw2 complex contributes to ATP-dependent chromatin remodeling in Saccharomyces cerevisiae.
- GO:0006338 GO:0006338 is the Gene Ontology biological-process term for chromatin remodeling.
- GO:0008623 GO:0008623 defines CHRAC as an ISWI complex involved in RNA polymerase II transcription, DNA replication, and DNA repair.
- DOI:10.1128/MCB.24.7.2605-2613.2004 McConnell et al. 2004 found that Dls1p was required for Isw2-dependent chromatin remodeling in vivo.

Mechanism graphs

CHRAC supports yeast chromatin remodeling (FUNCTION)

In Saccharomyces cerevisiae, Isw2, Itc1, Dpb4, and Dls1 form a CHRAC-like four-subunit Isw2 chromatin-remodeling complex.

Subject	Predicate	Object	Evidence
Isw2 CHRAC ATPase subunit	contributes to	CHRAC	`DOI:10.1128/MCB.24.7.2605-2613.2004` McConnell et al. 2004 found this constituent in a purified Saccharomyces cerevisiae four-subunit Isw2 complex.
Itc1 CHRAC ACF1-homolog subunit	contributes to	CHRAC	`DOI:10.1128/MCB.24.7.2605-2613.2004` McConnell et al. 2004 found this constituent in a purified Saccharomyces cerevisiae four-subunit Isw2 complex.
Dpb4 CHRAC histone-fold subunit	contributes to	CHRAC	`DOI:10.1128/MCB.24.7.2605-2613.2004` McConnell et al. 2004 found this constituent in a purified Saccharomyces cerevisiae four-subunit Isw2 complex.
Dls1 CHRAC histone-fold subunit	contributes to	CHRAC	`DOI:10.1128/MCB.24.7.2605-2613.2004` McConnell et al. 2004 found this constituent in a purified Saccharomyces cerevisiae four-subunit Isw2 complex.
CHRAC	enables	chromatin remodeling	`GO:0008623` GO:0008623 defines CHRAC as an ISWI complex with a role in RNA polymerase II transcription. `DOI:10.1128/MCB.24.7.2605-2613.2004` McConnell et al. 2004 found that Dls1p was required for Isw2-dependent chromatin remodeling in vivo.

Discussions

CURATION_TODO (OPEN): Curate exact source-neutral InterPro, Pfam, NCBIfam or UniProt family groundings for the CHRAC Isw2, Itc1, Dpb4, and Dls1 component classes when terms that denote those classes can be verified. Isw2 and Itc1 also occur in a two-subunit ACF-like complex, Dpb4 is shared with DNA polymerase epsilon, and available histone-fold or ATPase identifiers are broader than the CHRAC subunit classes, so exact grounding should avoid terms that do not denote these CHRAC roles.

Evidence

GO:0008623 Gene Ontology cellular-component term for CHRAC.
GO:0031010 Gene Ontology cellular-component parent term for ISWI-type complexes.
GO:0006338 Gene Ontology biological-process term for chromatin remodeling.
PMID:14673157 PubMed identifier for Iida and Araki 2004, the Molecular and Cellular Biology paper that described putative budding-yeast ISW2/yCHRAC.
DOI:10.1128/MCB.24.1.217-227.2004 DOI for Iida and Araki 2004, 'Noncompetitive counteractions of DNA polymerase epsilon and ISW2/yCHRAC for epigenetic inheritance of telomere position effect in Saccharomyces cerevisiae', verified through NCBI E-utilities.
PMID:15024052 PubMed identifier for McConnell et al. 2004, the Molecular and Cellular Biology paper that identified Dpb4 and Dls1 as Isw2 complex histone-fold subunits.
DOI:10.1128/MCB.24.7.2605-2613.2004 DOI for McConnell et al. 2004, 'Histone fold protein Dls1p is required for Isw2-dependent chromatin remodeling in vivo', verified through NCBI E-utilities.

Curation history

2026-09-27T02:40:57Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-27T02:42:10Z codex · EXPANDED_RECORD — Added chromatin-accessibility-complex synonymy, ISWI-type parentage, four budding-yeast constituent rows, yeast scope, chromatin-remodeling function, GO/PubMed/DOI evidence, a nonmechanistic function graph, and a subunit-grounding TODO.
2026-09-27T02:54:01Z codex · ADDRESS_REVIEW — Added direct McConnell et al. 2004 literature evidence to the CHRAC causal-graph edge that connects the complex to chromatin remodeling.

Source: data/structures/other/chrac.yaml