HIR complex

GO:0000417 · Other · Multiprotein complex · Proposed

A protein complex proposed to be involved in replication-independent nucleosome assembly, by promoting histone deposition onto DNA. For example, in Saccharomyces, the complex contains Hir1p, Hir2p, Hir3p, and Hpc2p. [GO:0000417]

Synonyms: HIRA 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
Hir1 HIR subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	HIR1	UNKNOWN	Protein constituent of the budding-yeast HIR histone deposition complex. `GO:0000417` GO:0000417 defines the Saccharomyces HIR complex as containing Hir1p. `DOI:10.1016/j.cub.2005.10.053` Green et al. 2005 reported that Hir1, Hir2, Hir3 and Hpc2 comprise the budding-yeast HIR complex.
Hir2 HIR subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	HIR2	UNKNOWN	Protein constituent of the budding-yeast HIR histone deposition complex. `GO:0000417` GO:0000417 defines the Saccharomyces HIR complex as containing Hir2p. `DOI:10.1016/j.cub.2005.10.053` Green et al. 2005 reported that Hir1, Hir2, Hir3 and Hpc2 comprise the budding-yeast HIR complex.
Hir3 HIR subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	HIR3	UNKNOWN	Protein constituent of the budding-yeast HIR histone deposition complex. `GO:0000417` GO:0000417 defines the Saccharomyces HIR complex as containing Hir3p. `DOI:10.1016/j.cub.2005.10.053` Green et al. 2005 reported that Hir1, Hir2, Hir3 and Hpc2 comprise the budding-yeast HIR complex.
Hpc2 HIR subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	HPC2	UNKNOWN	Protein constituent of the budding-yeast HIR histone deposition complex. `GO:0000417` GO:0000417 defines the Saccharomyces HIR complex as containing Hpc2p. `DOI:10.1016/j.cub.2005.10.053` Green et al. 2005 reported that Hir1, Hir2, Hir3 and Hpc2 comprise the budding-yeast HIR complex.

Taxonomic distribution

NCBITaxon:4932 Saccharomyces cerevisiae — COMMON: Budding yeast is the organism in which GO:0000417 defines the HIR complex as containing Hir1p, Hir2p, Hir3p and Hpc2p. [GO:0000417]

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — Green et al. 2005 showed that Hir1, Hir2, Hir3 and Hpc2 comprise the budding-yeast HIR complex that copurifies with Asf1. [DOI:10.1016/j.cub.2005.10.053]

Functions

nucleosome assembly GO:0006334 — The HIR complex cooperates with Asf1 in replication-independent histone deposition onto DNA.
- GO:0000417 GO:0000417 defines the HIR complex as involved in replication-independent nucleosome assembly.
- GO:0006334 GO:0006334 is the Gene Ontology biological-process term for nucleosome assembly.
- DOI:10.1016/j.cub.2005.10.053 Green et al. 2005 assayed replication-independent histone deposition by HIR complex and Asf1.

Mechanism graphs

HIR carries yeast replication-independent histone deposition (FUNCTION)

In Saccharomyces cerevisiae, Hir1p, Hir2p, Hir3p and Hpc2p form the HIR complex that cooperates with Asf1 in replication-independent histone deposition onto DNA.

Subject	Predicate	Object	Evidence
Hir1 HIR subunit	contributes to	HIR complex	`GO:0000417` GO:0000417 defines Hir1p as a HIR complex constituent.
Hir2 HIR subunit	contributes to	HIR complex	`GO:0000417` GO:0000417 defines Hir2p as a HIR complex constituent.
Hir3 HIR subunit	contributes to	HIR complex	`GO:0000417` GO:0000417 defines Hir3p as a HIR complex constituent.
Hpc2 HIR subunit	contributes to	HIR complex	`GO:0000417` GO:0000417 defines Hpc2p as a HIR complex constituent.
HIR complex	supports	nucleosome assembly	`GO:0000417` GO:0000417 defines the HIR complex as involved in replication-independent nucleosome assembly. `GO:0006334` GO:0006334 is the Gene Ontology biological-process term for nucleosome assembly. `DOI:10.1016/j.cub.2005.10.053` Green et al. 2005 assayed replication-independent histone deposition by the budding-yeast HIR complex and Asf1.

Discussions

CURATION_TODO (RESOLVED): Do not model Asf1 as a constituent of the HIR complex. Green et al. 2005 reported that Hir1, Hir2, Hir3 and Hpc2 comprise the budding-yeast HIR complex and that this complex copurifies with Asf1, supporting Asf1 as a histone-deposition partner rather than one of the four HIR constituents.
CURATION_TODO (OPEN): Resolve exact source-neutral family groundings for the HIR complex constituents. GO:0000417 defines the Saccharomyces Hir1p, Hir2p, Hir3p and Hpc2p proteins as HIR complex constituents. Exact cross-eukaryotic InterPro, Pfam, NCBIfam or UniProt family boundaries for these HIR subunit classes need narrower curation before the component labels can be grounded.

Evidence

GO:0000417 Gene Ontology cellular-component term for the HIR complex and its exact HIRA complex synonym.
GO:0032991 Gene Ontology cellular-component parent term for protein-containing complexes.
GO:0006334 Gene Ontology biological-process term for nucleosome assembly.
PMID:16303565 PubMed identifier for Green et al. 2005, the HIR complex and Asf1 paper cited by GO:0000417.
DOI:10.1016/j.cub.2005.10.053 DOI for Green et al. 2005, 'Replication-independent histone deposition by the HIR complex and Asf1', verified through NCBI E-utilities.
PMID:17180700 PubMed identifier for Mousson et al. 2007, the Asf1 histone-chaperone review cited by GO:0000417.
DOI:10.1007/s00412-006-0087-z DOI for Mousson et al. 2007, 'The histone chaperone Asf1 at the crossroads of chromatin and DNA checkpoint pathways', verified through NCBI E-utilities.

Curation history

2026-09-26T06:08:55Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-26T06:10:11Z codex · EXPANDED_RECORD — Added HIRA exact synonymy, protein-containing-complex parentage, four budding-yeast HIR constituent rows, yeast scope, nucleosome assembly function, GO/PubMed/DOI evidence, a nonmechanistic function graph, and a HIR subunit-grounding TODO.
2026-09-26T06:11:07Z codex · RECORDED_BOUNDARY_DECISION — Recorded a resolved component-boundary discussion explaining why Asf1 is not curated as one of the four HIR complex constituents.

Source: data/structures/other/hir_complex.yaml