POLQ

POLQ (DNA Polymerase Theta) is a protein coding gene. Among its related pathways are Cell Cycle Control of Chromosomal Replication and DNA Double-Strand Break Repair. Gene Ontology annotations related to this gene include nucleic acid binding and damaged DNA binding. An important paralog of the gene is ASCC3.

polymerase (DNA directed), theta

DNA polymerase that promotes microhomology-mediated end-joining (MMEJ), an alternative non-homologous end-joining (NHEJ) machinery triggered in response to double-strand breaks in DNA (PubMed:25642963, PubMed:25643323).
MMEJ is an error-prone repair pathway that produces deletions of sequences from the strand being repaired and promotes genomic rearrangements, such as telomere fusions, some of them leading to cellular transformation (PubMed:25642963, PubMed:25643323).
POLQ acts as an inhibitor of homology-recombination repair (HR) pathway by limiting RAD51 accumulation at resected ends (PubMed:25642963).
POLQ-mediated MMEJ may be required to promote the survival of cells with a compromised HR repair pathway, thereby preventing genomic havoc by resolving unrepaired lesions (By similarity).
The polymerase acts by binding directly the 2 ends of resected double-strand breaks, allowing microhomologous sequences in the overhangs to form base pairs. It then extends each strand from the base-paired region using the opposing overhang as a template. Requires partially resected DNA containing 2 to 6 base pairs of microhomology to perform MMEJ (PubMed:25643323).
The polymerase activity is highly promiscuous: unlike most polymerases, promotes extension of ssDNA and partial ssDNA (pssDNA) substrates (PubMed:18503084, PubMed:21050863, PubMed:22135286).
Also exhibits low-fidelity DNA synthesis, translesion synthesis and lyase activity, and it is implicated in interstrand-cross-link repair, base excision repair and DNA end-joining (PubMed:14576298, PubMed:18503084, PubMed:19188258, PubMed:24648516).
Involved in somatic hypermutation of immunoglobulin genes, a process that requires the activity of DNA polymerases to ultimately introduce mutations at both A/T and C/G base pairs (By similarity).

Base-excision repairManual Assertion Based On ExperimentIDA:UniProtKB
Cellular response to DNA damage stimulusManual Assertion Based On ExperimentIDA:UniProtKB
DNA repairManual Assertion Based On ExperimentTAS:ProtInc
DNA-templated DNA replicationIEA:InterPro
Double-strand break repairManual Assertion Based On ExperimentIDA:UniProtKB
Double-strand break repair via alternative nonhomologous end joiningManual Assertion Based On ExperimentIDA:UniProtKB
Negative regulation of double-strand break repair via homologous recombinationManual Assertion Based On ExperimentIDA:UniProtKB
Protein homooligomerizationManual Assertion Based On ExperimentIDA:UniProtKB
Somatic hypermutation of immunoglobulin genesISS:UniProtKB

Nucleus
Chromosome
Enriched in chromatin in response to ultaviolet (UV) light (PubMed:25642963).
Binds to chromatin during early G1 (PubMed:24989122).

Breast cancer (BC):
A common malignancy originating from breast epithelial tissue. Breast neoplasms can be distinguished by their histologic pattern. Invasive ductal carcinoma is by far the most common type. Breast cancer is etiologically and genetically heterogeneous. Important genetic factors have been indicated by familial occurrence and bilateral involvement. Mutations at more than one locus can be involved in different families or even in the same case.