TY - JOUR T1 - Substrate Selectivity of Mouse <em>N-</em>Acetyltransferases 1, 2, and 3 Expressed in COS-1 Cells JF - Drug Metabolism and Disposition JO - Drug Metab Dispos SP - 502 LP - 505 VL - 26 IS - 5 AU - Lourdes Estrada-Rodgers AU - Gerald N. Levy AU - Wendell W. Weber Y1 - 1998/05/01 UR - http://dmd.aspetjournals.org/content/26/5/502.abstract N2 - Two human acetyl-CoA:arylamine N-acetyltransferases (NAT1 and NAT2) have been identified. Therapeutic and carcinogenic agents that are substrates for these isoenzymes (including isoniazid, sulfamethazine, p-aminobenzoic acid, 5-aminosalicyclic acid, and 2-aminofluorene) have been used to evaluate the role of theN-acetylation polymorphisms of NAT1 and NAT2 in the treatment of disease and differential risk of various cancers among individuals of differing acetylator phenotypes. The mouse is frequently used as a model of the human acetylator polymorphism. As three Nat isoenzymes have been identified in mouse, it is necessary to determine the selectivity of mouse Nats toward common NAT substrates. In the present study, Nat1*, Nat2*8, andNat3* were expressed in COS-1 cells, and their substrate selectivity was evaluated with various substrates. Under the conditions used, mouse Nat2 had 20-, 2.4-, and 5.4-fold higher catalytic activity for p-aminobenzoic acid, 5-aminosalicylic acid, and 2-aminofluorene, respectively, than Nat1. IsoniazidN-acetylation was catalyzed only by mouse Nat1. For the substrates tested in this study, mouse Nat3 exhibited activity only toward 5-aminosalicylic acid and only at 1/20 the activity shown by Nat2. In addition, p-aminobenzoylglutamate, the first endogenous NAT substrate identified, was selective for mouse Nat2. These results further support the functional analogy of mouse Nat2 and human NAT1. The American Society for Pharmacology and Experimental Therapeutics ER -