Mouse steroid 15 alpha-hydroxylase gene family: identification of type II P-450(15)alpha as coumarin 7-hydroxylase.
We identified type II P-450(15)alpha as mouse coumarin 7-hydroxylase (P-450coh). Unlike type I P-450(15)alpha, the other member within the mouse steroid 15 alpha-hydroxylase gene family, type II catalyzed little steroid 15 alpha-hydroxylase activity, yet structurally there were only 11 substitutions between type I and type II P-450(15)alphaS within their 494 amino acid residues (Lindberg et al., 1989), and the N-terminal sequence (21 residues) of P-450coh was identical with that of both P-450(15)alphaS. Induction by pyrazole of coumarin 7-hydroxylase activity correlated well with the increase of type II P-450(15)alpha mRNA in 129/J male and female mice. Pyrazole, on the other hand, was less in males or not effective in females in inducing the 15 alpha-hydroxylase activity and type I P-450(15)alpha mRNA. Expression of type I and II in COS-1 cells revealed that the latter catalyzed coumarin 7-hydroxylase activity at 10 to approximately 14 pmol min-1 (mg of cellular protein)-1. The former, on the other hand, had a high testosterone 15 alpha-hydroxylase but little coumarin 7-hydroxylase activity. It was concluded, therefore, that type II P-450(15)alpha is the mouse coumarin 7-hydroxylase. Identification of type II as the P-450 specific to coumarin 7-hydroxylase activity and characterization of its cDNA and gene, therefore, were significant advances toward understanding the basis of genetic regulation of this activity in mice (known as Coh locus).
Negishi
M
M
Pharmacogenetics Section, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709.
Lindberg
R
R
Burkhart
B
B
Ichikawa
T
T
Honkakoski
P
P
Lang
M
M
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases; D065637:Cytochrome P-450 CYP2A6; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism; D000072467:Cytochrome P450 Family 2; D004247:DNA / Q000235:genetics; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D005786:Gene Expression Regulation; D008297:Male; D051379:Mice; D006899:Mixed Function Oxygenases / Q000235:genetics* / Q000378:metabolism; D005810:Multigene Family; D011720:Pyrazoles / Q000494:pharmacology; D013250:Steroid Hydroxylases / Q000235:genetics* / Q000378:metabolism
D011720:Pyrazoles; C031280:pyrazole; D004247:DNA; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D013250:Steroid Hydroxylases; D001189:Aryl Hydrocarbon Hydroxylases; C460223:Cyp2a4 protein, mouse; D065637:Cytochrome P-450 CYP2A6; D000072467:Cytochrome P450 Family 2; C050356:steroid 15-alpha-hydroxylase