Gene for the Catalytic Subunit of the Human DNA-Activated Protein Kinase Maps to the Site of the XRCC7 Gene on Chromosome 8

The DNA-activated serine/threonine protein kinase (DNA-PK) is composed of a large (≈460 kDa) catalytic polypeptide (DNA-PKcs) and Ku, a heterodimeric DNA-binding component (p70/p80) that targets DNA-PKcsto DNA. A 41-kbp segment of the DNA-PKcsgene was isolated, and a 7902-bp segment was sequenced. The sequence contains a polymorphic Pvu II restriction enzyme site, and comparing the sequence with that of the cDNA revealed the positions of nine exons. The DNA-PKcsgene was mapped to band q11 of chromosome 8 by in situ hybridization. This location is coincident with that of XRCC7, the gene that complements the DNA double-strand break repair and V(D)J recombination defects (where V is variable, D is diversity, and J is joining) of hamster V3 and murine severe combined immunodeficient (scid) cells.