POLK (DNA Polymerase Kappa)
A specialized translesion synthesis DNA polymerase involved in replication past DNA damage and genomic stability.
Gene Information Card
| Symbol | POLK |
|---|---|
| Full Name | DNA polymerase kappa |
| Gene Type | protein-coding |
| Chromosomal Location | 5q13.3 |
| NCBI Gene ID | 51426 ncbi.nlm.nih.gov/gene/51426 |
| Ensembl ID | ENSG00000102984 |
| UniProt ID | Q9UBT6 |
| OMIM ID | 605275 |
| HGNC ID | 9183 |
| Aliases | DINB1, POLQ, POLKAPPA |
Description
POLK encodes DNA polymerase kappa, a member of the Y-family of DNA polymerases specialized in translesion synthesis (TLS). This enzyme allows replication past DNA lesions that block replicative polymerases, such as cyclobutane pyrimidine dimers and certain chemical adducts. POLK is error-prone on undamaged DNA but can perform relatively accurate bypass of specific lesions. It plays a role in maintaining genomic stability and is implicated in cancer susceptibility and chemoresistance.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Xeroderma Pigmentosum Variant (XPV) | Defective translesion synthesis of UV-induced photoproducts leads to increased mutagenesis and skin cancer risk. | ClinVar, OMIM |
| Colorectal Cancer | POLK overexpression and somatic mutations contribute to tumor progression and chemoresistance. | COSMIC, NCBI |
| Lung Cancer | POLK polymorphisms and altered expression associated with increased risk and poor prognosis. | NCBI, COSMIC |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Testis | 12.5 | Medium |
| Skin | 8.3 | Medium |
| Lung | 6.1 | Low |
| Colon | 5.4 | Low |
| Breast | 4.2 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 9.8 | Cervical cancer cell line |
| A549 | 7.5 | Lung carcinoma cell line |
| HCT116 | 6.3 | Colorectal carcinoma cell line |
| MCF7 | 5.1 | Breast cancer cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.943C>T (p.Arg315*) | Nonsense | <0.01% | Loss of function; truncation of catalytic domain |
| c.1196A>G (p.Glu399Gly) | Missense | 0.02% | Reduced polymerase activity; altered lesion bypass |
| c.1634T>C (p.Leu545Pro) | Missense | 0.01% | Impaired TLS efficiency; associated with XPV phenotype |
Mutation functional classification
Loss of Function (LOF)
Nonsense and frameshift mutations that truncate the protein or disrupt the polymerase domain lead to loss of TLS activity, increasing UV sensitivity and mutagenesis.
Gain of Function (GOF)
Missense mutations that enhance processivity or alter lesion specificity may promote error-prone bypass and genomic instability, potentially driving tumorigenesis.
Dominant Negative (DN)
Certain missense mutations (e.g., p.Glu399Gly) produce a protein that interferes with wild-type POLK function, reducing overall TLS capacity.
View complete mutation data：
Gene Ontology (GO)
| • DNA binding | • DNA-directed DNA polymerase activity |
| • damaged DNA binding | • nucleotidyltransferase activity |
| • translesion synthesis | • nucleus |
| • DNA replication | • response to UV |
Pathways
• Translesion synthesis by Y-family DNA polymerases
• DNA damage bypass
• Nucleotide excision repair (NER) - associated
Protein Summary
DNA polymerase kappa (POLK) is a 870-amino acid protein with a catalytic core typical of Y-family polymerases, including finger, palm, thumb, and little finger domains. It lacks 3'-5' exonuclease proofreading activity, resulting in low fidelity on undamaged templates. POLK efficiently bypasses N2-dG adducts and UV-induced thymine dimers. Its expression is cell-cycle regulated and induced by DNA damage. The protein interacts with PCNA and other TLS components to facilitate lesion bypass during replication.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| POLK Knockout HEK293 Cell Line | EDJ-KQ3042 | Human | 51426 | Details Get a Quote |
| POLK Knockout A-549 Cell Line | EDJ-KQ24282 | Human | 51426 | Details Get a Quote |
| POLK Knockout HCT 116 Cell Line | EDJ-KQ24283 | Human | 51426 | Details Get a Quote |
| POLK Knockout HeLa Cell Line | EDJ-KQ24284 | Human | 51426 | Details Get a Quote |
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