This gene encodes a member of the Y family of specialized DNA polymerases. It copies undamaged DNA with a lower fidelity than other DNA-directed polymerases. However， it accurately replicates UV-damaged DNA; when thymine dimers are present， this polymerase inserts the complementary nucleotides in the newly synthesized DNA， thereby bypassing the lesion and suppressing the mutagenic effect of UV-induced DNA damage. This polymerase is thought to be involved in hypermutation during immunoglobulin class switch recombination. Mutations in this gene result in XPV， a variant type of xeroderma pigmentosum. Several transcript variants encoding different isoforms have been found for this gene.