Source:http://linkedlifedata.com/resource/umls/id/C0140145
NCI: APEX Nuclease, encoded by the APE1 gene, is a ubiquitous monomeric apurinic/apyrimidinic DNA repair endonuclease (AP/EXOA family) with 3-prime-, 5-prime-exonuclease, DNA 3-prime repair diesterase, and DNA 3-prime-phosphatase activities. The constitutive gene contains five exons spanning 2.64 kb; the first exon is untranslated. The 0.5 kb upstream DNA contains only a possible CCAAT box and no other regulatory sites or a TATA box. A potent activator of p53 protein, APE1 may protect against cell lethality and suppress mutations produced by spontaneous hydrolysis, by chemicals and radiation, or by DNA glycosylases that remove abnormal bases from DNA. Abasic sites that can block DNA replication and cause mutations must be corrected to restore genetic integrity. A repressor of the PTH gene, APE binds to promoter negative Ca(2+)-response elements, which are also present in the APE1 gene.