nuclear origin of replication recognition complex

GO:0005664 · Other · Multiprotein complex · Proposed

A multisubunit complex that is located at the replication origins of a chromosome in the nucleus. [GO:0005664]

Synonyms: eukaryotic ORC; nuclear ORC

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
Orc1 subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	ORC1	UNKNOWN	Named Saccharomyces constituent of the origin recognition complex. `PMID:22405012` The PubMed abstract for the 2012 Structure cryo-EM paper reports that the six Saccharomyces cerevisiae ORC subunits Orc1, Orc4, Orc5, Orc2, Orc3 and Orc6 are arranged around ORC-Cdc6 bound to origin DNA.
Orc2 subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	ORC2	UNKNOWN	Named Saccharomyces constituent of the origin recognition complex. `PMID:22405012` The PubMed abstract for the 2012 Structure cryo-EM paper reports that the six Saccharomyces cerevisiae ORC subunits Orc1, Orc4, Orc5, Orc2, Orc3 and Orc6 are arranged around ORC-Cdc6 bound to origin DNA.
Orc3 subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	ORC3	UNKNOWN	Named Saccharomyces constituent of the origin recognition complex. `PMID:22405012` The PubMed abstract for the 2012 Structure cryo-EM paper reports that the six Saccharomyces cerevisiae ORC subunits Orc1, Orc4, Orc5, Orc2, Orc3 and Orc6 are arranged around ORC-Cdc6 bound to origin DNA.
Orc4 subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	ORC4	UNKNOWN	Named Saccharomyces constituent of the origin recognition complex. `PMID:22405012` The PubMed abstract for the 2012 Structure cryo-EM paper reports that the six Saccharomyces cerevisiae ORC subunits Orc1, Orc4, Orc5, Orc2, Orc3 and Orc6 are arranged around ORC-Cdc6 bound to origin DNA.
Orc5 subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	ORC5	UNKNOWN	Named Saccharomyces constituent of the origin recognition complex. `PMID:22405012` The PubMed abstract for the 2012 Structure cryo-EM paper reports that the six Saccharomyces cerevisiae ORC subunits Orc1, Orc4, Orc5, Orc2, Orc3 and Orc6 are arranged around ORC-Cdc6 bound to origin DNA.
Orc6 subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	ORC6	UNKNOWN	Named Saccharomyces constituent of the origin recognition complex. `PMID:22405012` The PubMed abstract for the 2012 Structure cryo-EM paper reports that the six Saccharomyces cerevisiae ORC subunits Orc1, Orc4, Orc5, Orc2, Orc3 and Orc6 are arranged around ORC-Cdc6 bound to origin DNA.

Taxonomic distribution

NCBITaxon:2759 Eukaryota — COMMON: The ORC protein-family review reports that Orc1-Orc5 appear to be present in all eukaryotes and that Orc6 is poorly conserved outside budding yeast. [PMID:19344485]

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — Bell and Stillman originally purified the origin recognition complex from budding yeast and assayed origin-specific DNA binding in Saccharomyces cerevisiae. [PMID:1579162]

Functions

DNA replication origin binding GO:0003688 — The origin recognition complex recognizes DNA replication origins in an ATP-dependent manner.
- GO:0003688 GO:0003688 is the Gene Ontology molecular-function term for DNA replication origin binding.
- PMID:1579162 The PubMed abstract for Bell and Stillman 1992 reports ATP-dependent origin-specific DNA binding by the Saccharomyces cerevisiae origin recognition complex.

Mechanism graphs

ORC binds replication origins (FUNCTION)

The six Saccharomyces Orc subunits form an origin recognition complex that binds replication-origin DNA.

Subject	Predicate	Object	Evidence
Orc1 subunit	contributes to	nuclear origin of replication recognition complex	`PMID:22405012` The PubMed abstract for the 2012 Structure cryo-EM paper names Orc1, Orc4, Orc5, Orc2, Orc3 and Orc6 as the six Saccharomyces ORC subunits.
Orc2 subunit	contributes to	nuclear origin of replication recognition complex	`PMID:22405012` The PubMed abstract for the 2012 Structure cryo-EM paper names Orc1, Orc4, Orc5, Orc2, Orc3 and Orc6 as the six Saccharomyces ORC subunits.
Orc3 subunit	contributes to	nuclear origin of replication recognition complex	`PMID:22405012` The PubMed abstract for the 2012 Structure cryo-EM paper names Orc1, Orc4, Orc5, Orc2, Orc3 and Orc6 as the six Saccharomyces ORC subunits.
Orc4 subunit	contributes to	nuclear origin of replication recognition complex	`PMID:22405012` The PubMed abstract for the 2012 Structure cryo-EM paper names Orc1, Orc4, Orc5, Orc2, Orc3 and Orc6 as the six Saccharomyces ORC subunits.
Orc5 subunit	contributes to	nuclear origin of replication recognition complex	`PMID:22405012` The PubMed abstract for the 2012 Structure cryo-EM paper names Orc1, Orc4, Orc5, Orc2, Orc3 and Orc6 as the six Saccharomyces ORC subunits.
Orc6 subunit	contributes to	nuclear origin of replication recognition complex	`PMID:22405012` The PubMed abstract for the 2012 Structure cryo-EM paper names Orc1, Orc4, Orc5, Orc2, Orc3 and Orc6 as the six Saccharomyces ORC subunits.
nuclear origin of replication recognition complex	supports	DNA replication origin binding	`GO:0003688` GO:0003688 is the molecular-function term for DNA replication origin binding. `PMID:1579162` The PubMed abstract for Bell and Stillman 1992 reports origin-specific DNA binding by the Saccharomyces cerevisiae origin recognition complex.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral family groundings for Orc1-Orc6 origin-recognition-complex subunit classes. PMID:22405012 identifies Orc1, Orc4, Orc5, Orc2, Orc3 and Orc6 as the six Saccharomyces ORC subunits, while PMID:19344485 reports that Orc1-Orc5 appear to be present in all eukaryotes and that Orc6 is poorly conserved outside budding yeast. This record therefore leaves ORC subunit components label-only rather than asserting unverified exact InterPro, Pfam, NCBIfam or UniProtKB family CURIEs.

Evidence

GO:0005664 Gene Ontology cellular-component term for the nuclear origin of replication recognition complex.
GO:0000808 Gene Ontology cellular-component parent term for origin recognition complexes.
GO:0140513 Gene Ontology cellular-component parent term for nuclear protein-containing complexes.
GO:0003688 Gene Ontology molecular-function term for DNA replication origin binding.
PMID:1579162 PubMed record for the Bell and Stillman paper that purified a budding-yeast multiprotein ORC with ATP-dependent binding to cellular replication origins.
PMID:19344485 PubMed record for the origin-recognition-complex protein-family review covering Orc1-Orc6 conservation across eukaryotes.
PMID:22405012 PubMed record for a Saccharomyces cerevisiae ORC-Cdc6-origin-DNA cryo-EM paper that places the six ORC subunits.

Curation history

2026-09-27T17:40:43Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-27T17:41:36Z codex · EXPANDED_RECORD — Added GO ORC synonymy, origin-recognition and nuclear protein-containing-complex parentage, six reviewed-label-only Orc constituent rows, Eukaryota scope, budding-yeast canonical evidence, DNA-origin-binding function evidence, GO/PubMed evidence, a nonmechanistic function graph, and an ORC subunit-grounding TODO.
2026-09-27T17:42:16Z codex · REFINED_RECORD — Normalized ORC component role wording and kept the Eukaryota taxonomic-scope note focused on its PubMed reference.
2026-09-27T17:48:34Z codex · FIXED_ID_LABEL — Aligned the ORC causal-graph GO:0005664 structure-node label with the current GO canonical label.

Source: data/structures/other/nuclear_origin_of_replication_recognition_complex.yaml