DNA polymerase theta (pol θ) is encoded in the genomes of many eukaryotes, though not in
fungi. Pol θ is encoded by the POLQ gene in mammalian cells. The C-terminal third of the
protein is a family A DNA polymerase with additional insertion elements relative to
prokaryotic homologs. The N-terminal third is a helicase-like domain with DNA-dependent
ATPase activity. Pol θ is important in the repair of genomic double-strand breaks (DSBs)
from many sources. These include breaks formed by ionizing radiation and topoisomerase …