Description
During base excision repair (BER) DNA polymerase β (Pol β) is recruited by APE1. Pol β has two distinct domains, the larger is the polymerase domain itself, whereas a small basic N-terminal domain contains an AP lyase activity that excises the abasic sugar-phosphate residue at the strand break. Pol β also interacts with XRCC1, DNA ligase III and poly(ADP-ribose) polymerase in the repair of DNA single strand breaks. Pol β plays a role in both BER pathways, "single-nucleotide" and "long patch". It is the most inaccurate of the six DNA polymerases found in mammalian cells. Overexpression of Pol β, as found in some human tumors, could confer an increase in spontaneous mutagenesis. It has been further suggested that Pol β does not excise 5'-oxidized AP sites induced by reactive oxygen species (ROS)