Human apurinic endonuclease gene (APE): structure and genomic mapping (chromosome 14q11.2-12).

Abasic (AP) sites in DNA are produced spontaneously and by many genotoxic agents. The repair of such damages is initiated by AP endonucleases, which are evidently ubiquitous. We employed the recently cloned cDNA, APE, that encodes the major human AP endonuclease, to isolate large genomic fragments that contain the intact APE gene. The sequence of 3 kb encompassing APE was determined (GenBank Accession No. M99703). The APE gene contains four small introns (ranging 130 to 566 bp) and five exons, the first of which is untranslated. The 0.5 kb of DNA sequence upstream of APE did revealed only a possible CCAAT box, but no other regulatory sites or a TATA box, consistent with the constitutive expression of AP endonuclease activity observed in other studies. The location of APE in the human genome was mapped to chromosome 14, bands q11.2-12, by fluorescence in situ hybridization of metaphase cells with DNA from the genomic clones and subclones. Although this locus has not been associated causally with genetic diseases of DNA repair, some translocations that affect 14q11.2-12 could compromise APE and lead to genetic instability.