Cloning CYP2D21 and CYP3A22 cDNAs from liver of miniature pigs

To compare the identity of the primary structure of drug-metabolizing cytochrome P450 between miniature pigs and humans, two cDNA clones, coding for miniature pig CYP2D21 and CYP3A22, were isolated. The deduced amino acid sequences of CYP2D21 and CYP3A22 were 78.3 and 75.0% identical to human CYP2D6 and CYP3A4, respectively. These values were nearly the same as those of bovine, dog, and some rodent isoforms, and 12.2 to 18.4% lower than those of nonhuman primates such as cynomolgus monkeys, Japanese monkey, and marmosets. These data indicate that miniature pig P450s are genetically not so close as monkey P450s to human P450s as previously expected. The recombinant CYP2D21 enzyme, however, showed bufuralol 1'-hydroxylase activity, suggesting that miniature pig CYP2D21 is capable of metabolizing some of the same substrates associated with human CYP2D6 despite its low identity to human counterparts.