Cloning and Chromosomal Mapping of the Human DNA Polymerase θ (POLQ), the Eighth Human DNA Polymerase

We have cloned the cDNA for the eighth human DNA polymerase, DNA polymerase θ. The human cDNA encodes a putative DNA polymerase of 1762 amino acids with a calculated molecular mass of 198 kDa. The derived protein sequence is homologous to the Drosophila melanogaster mus308 protein product, a putative DNA polymerase–helicase involved in repair of interstrand crosslinks. The C-terminal region contains the canonical DNA polymerase motifs A, B, and C found in the family A type of DNA polymerases, which includes Escherichia coli polymerase I. The N-terminal region contains a putative ATP binding domain but not motifs for a helicase. The gene was mapped by radiation hybrid analysis to chromosome 3q within an interval flanked by proximal marker D3S1303 and distal marker D3S3576 and, based on proximity to a gene that has been mapped cytogenetically, within band 3q13.31.