Apurinic/apyrimidinic (AP) sites occur frequently in DNA molecules by spontaneous hydrolysis, by DNA damaging agents or by DNA glycosylases that remove specific abnormal bases. AP sites are pre-mutagenic lesions that can prevent normal DNA replication so the cell contains systems to identify and repair such sites. Class II AP endonucleases cleave the phosphodiester backbone 5 to the AP site. This gene encodes the major AP endonuclease in human cells. Splice variants have been found for this gene, all encode the same protein. [provided by RefSeq, Jul 2008],catalytic activity:The C-O-P bond 3 to the apurinic or apyrimidinic site in DNA is broken by a beta-elimination reaction, leaving a 3-terminal unsaturated sugar and a product with a terminal 5-phosphate.,function:Repairs oxidative DNA damages in vitro. May have a role in protection against cell lethality and suppression of mutations. Removes the blocking groups from the 3-termini of the DNA strand breaks generated by ionizing radiations and bleomycin.,similarity:Belongs to the DNA repair enzymes AP/exoA family.,subunit:Monomer. Component of the SET complex, which also contains SET, ANP32A, HMGB2 and NME1.,
