A DNA repair mechanism used to remove mutated bases. DNA glycosylase excises the mutated base but creates an apurinic/apyrimidinic (AP) site; this is recognized by AP endonuclease which cuts the strand upstream (5′) of the mutated base and polymerase I can then add a new (correct) base to the free 3′ end by pairing with the undamaged strand. Ligase then seals the join. In short-patch repair a single nucleotide is replaced; in long-patch repair 2–10 nucleotides are replaced.
Subjects: Medicine and Health.