POLD2: DNA Polymerase Delta 2, Accessory Subunit
Essential component of the DNA polymerase delta complex involved in DNA replication and repair
Gene Information Card
| Symbol | POLD2 |
|---|---|
| Full Name | DNA Polymerase Delta 2, Accessory Subunit |
| Gene Type | Protein coding |
| Chromosomal Location | 7p13 |
| NCBI Gene ID | 5425 ncbi.nlm.nih.gov/gene/5425 |
| Ensembl ID | ENSG00000106628 |
| UniProt ID | P49005 |
| OMIM ID | 600815 |
| HGNC ID | 9176 |
| Aliases | p50, DNA polymerase delta subunit 2 |
Description
POLD2 encodes the 50 kDa accessory subunit of DNA polymerase delta (Pol δ), a heterotetrameric enzyme essential for eukaryotic DNA replication and repair. The POLD2 subunit stabilizes the complex and contributes to processivity and interaction with proliferating cell nuclear antigen (PCNA). It is involved in lagging strand synthesis, base excision repair, and mismatch repair.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Colorectal cancer | Somatic mutations in POLD2 may impair proofreading and increase mutation rate | COSMIC; PMID: 23508103 |
| Breast cancer | Overexpression of POLD2 associated with poor prognosis | TCGA; PMID: 29174464 |
| Immunodeficiency with DNA repair defects | Biallelic POLD2 variants cause reduced Pol δ activity and impaired V(D)J recombination | ClinVar; PMID: 31447097 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Testis | 28.5 | High |
| Bone marrow | 15.2 | Medium |
| Brain cortex | 9.8 | Medium |
| Liver | 6.3 | Low |
| Heart | 5.1 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 22.4 | Cervical cancer cell line |
| HEK293 | 18.7 | Embryonic kidney |
| HCT116 | 25.1 | Colorectal carcinoma |
| MCF7 | 14.3 | Breast cancer |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1A>G (p.Met1?) | Missense | <0.01% | Loss of start codon, likely loss of function |
| c.632C>T (p.Thr211Met) | Missense | 0.02% | Reduced Pol δ activity |
| c.1045G>A (p.Glu349Lys) | Missense | 0.01% | Impaired PCNA interaction |
Mutation functional classification
Loss of Function (LOF)
Nonsense or frameshift variants leading to truncated protein or nonsense-mediated decay
Gain of Function (GOF)
Not reported in literature
Dominant Negative (DN)
Missense variants that disrupt complex assembly without complete loss of wild-type allele
View complete mutation data：
Gene Ontology (GO)
| • DNA replication (GO:0006260) | • DNA repair (GO:0006281) |
| • DNA polymerase activity (GO:0034061) | • Protein binding (GO:0005515) |
| • Nucleus (GO:0005634) |
Pathways
• DNA replication (KEGG hsa03030)
• Mismatch repair (KEGG hsa03430)
• Base excision repair (KEGG hsa03410)
• Fanconi anemia pathway (KEGG hsa03460)
Protein Summary
POLD2 is a 50 kDa accessory subunit of DNA polymerase delta, forming a heterotetramer with POLD1, POLD3, and POLD4. It stabilizes the catalytic subunit and enhances processivity. The protein contains an oligonucleotide/oligosaccharide-binding (OB) fold domain that mediates interactions with DNA and PCNA. POLD2 is ubiquitously expressed with highest levels in testis and bone marrow.
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