POLN
Description
The POLN (DNA polymerase nu) is a protein-coding gene located on chromosome 4.
Polymerase (DNA directed) nu is a protein in humans that is encoded by the POLN gene. It is a family A DNA polymerase, considered to be the least effective of the polymerase enzymes. However, DNA polymerase nu plays an active role in homology repair during cellular responses to crosslinks, fulfilling its role in a complex with helicase.
DNA polymerase nu (POLN) is a low-fidelity DNA polymerase that frequently makes errors during DNA replication, particularly inserting the wrong nucleotide (dTTP instead of dGTP, or vice versa). It is the least accurate of the DNA polymerase A family, which includes POLG and POLQ. Despite its error-proneness, POLN can accurately replicate DNA past certain types of DNA damage, such as 5S-thymine glycol. It can also efficiently copy DNA past nicks and gaps in the DNA strand. POLN does not have the ability to proofread its own work, as it lacks exonuclease activity. POLN is also known to preferentially insert dT regardless of the template sequence, further contributing to its error-prone nature. POLN is thought to be involved in translesion DNA synthesis (TLS) during interstrand cross-link (ICL) repair, as well as during DNA replication blockage by large DNA lesions. It may also play a role in bypassing certain DNA-protein and DNA-DNA cross-links and in increasing cellular tolerance to DNA cross-linking agents. POLN has been shown to participate in the repair of DNA cross-links and double-strand break (DSB) resistance, likely by interacting with other proteins involved in DNA repair pathways. Specifically, POLN is involved in FANCD2-mediated repair and forms a complex with HELQ helicase, which is important for homologous recombination (HR) repair and protection against DNA cross-links.
POLN is also known as POL4P.
