ORC2 (Origin Recognition Complex Subunit 2)
A core component of the origin recognition complex essential for DNA replication initiation
Gene Information Card
| Symbol | ORC2 |
|---|---|
| Full Name | Origin recognition complex subunit 2 |
| Gene Type | Protein coding |
| Chromosomal Location | 2q33.1 |
| NCBI Gene ID | 4999 ncbi.nlm.nih.gov/gene/4999 |
| Ensembl ID | ENSG00000115942 |
| UniProt ID | Q13416 |
| OMIM ID | 601182 |
| HGNC ID | 8489 |
| Aliases | ORC2L, ORC2L1 |
Description
ORC2 encodes subunit 2 of the origin recognition complex (ORC), a six-subunit ATPase complex that binds to replication origins and is essential for the initiation of DNA replication in eukaryotic cells. ORC2 serves as a scaffold for the assembly of the pre-replication complex and is involved in cell cycle control, chromatin organization, and sister chromatid cohesion.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Meier-Gorlin syndrome 2 | Loss-of-function mutations in ORC2 impair origin recognition complex assembly, leading to reduced DNA replication licensing and cell proliferation defects, resulting in microcephaly, short stature, and skeletal abnormalities. | OMIM #617063; PMID: 28165345 |
| Primary microcephaly | ORC2 mutations disrupt neural progenitor cell proliferation during brain development, causing reduced brain size. | ClinVar; PMID: 28165345 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Testis | 12.5 | Medium |
| Lymph node | 10.3 | Medium |
| Bone marrow | 9.8 | Medium |
| Brain | 7.2 | Low |
| Liver | 6.1 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 14.2 | Cervical carcinoma cell line |
| HEK 293 | 13.5 | Embryonic kidney cells |
| K562 | 11.8 | Leukemia cell line |
| HepG2 | 10.1 | Hepatocellular carcinoma |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1A>G (p.Met1?) | Missense | Rare | Loss of start codon, likely loss of function |
| c.412C>T (p.Arg138Trp) | Missense | Rare | Impaired ORC complex assembly |
| c.1045C>T (p.Arg349*) | Nonsense | Rare | Premature truncation, loss of function |
Mutation functional classification
Loss of Function (LOF)
Most ORC2 mutations are loss-of-function, leading to reduced DNA replication licensing and cell proliferation.
Gain of Function (GOF)
No gain-of-function mutations reported for ORC2.
Dominant Negative (DN)
Not described; ORC2 mutations are typically recessive.
View complete mutation data：
Gene Ontology (GO)
| • DNA replication origin binding (GO:0003688) | • Origin recognition complex (GO:0000808) |
| • DNA replication initiation (GO:0006270) | • Cell cycle (GO:0007049) |
| • Chromatin binding (GO:0003682) |
Pathways
• Cell cycle (KEGG hsa04110)
• DNA replication (KEGG hsa03030)
• Pre-replication complex assembly (Reactome R-HSA-68874)
Protein Summary
ORC2 is a 577-amino acid protein that forms part of the six-subunit origin recognition complex. It contains an AAA+ ATPase domain and is essential for ATP-dependent binding to replication origins. ORC2 also interacts with other replication factors such as CDC6 and CDT1 to license origins during G1 phase. The protein is ubiquitously expressed and localizes to the nucleus.
Related Services
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