Base Excision Repair

Overview

First, a glycolyase cuts the damaged base off of its sugar. The site is now referred to as an AP site (apurinic/apyrimidinic). This AP site is then recognized and cut by AP lyase or AP endonuclease, creating a single-stranded break. A polymerase then adds a new nucleotide using the opposite strand as a template. The strand is then sealed with DNA ligase.