Chromosome mapping of the genes for murine arylamine N-acetyltransferases (NATs), enzymes involved in the metabolism of carcinogens: identification of a novel upstream noncoding exon for murine Nat2.

Arylamine N-acetyltransferases (NATs) catalyse acetylation reactions which can result in either detoxification or activation of arylamine carcinogens. The human NAT loci (NAT1, NAT2, and a pseudogene, NATP) have been mapped to human chromosome 8p22, a region frequently deleted in tumours. There are three functional genes in mice (Nat1, Nat2, and Nat3) encoding for three NAT isoenzymes. Different alleles at the Nat2 locus are responsible for the acetylation polymorphism identified in different mouse strains. We show that Nat3 is close to Nat1 and Nat2, by screening of a P1 artificial chromosome (PAC) library and provide cytogenetic evidence for co-localisation of the three genes in chromosome region 8 B3.1-B3.3. The Nat region of mouse and human is homologous. We also provide sequence information and a restriction map in the vicinity of Nat1 and Nat2 and describe a noncoding exon located 6 kb upstream of the Nat2 coding region.