Mouse steroid 15 alpha-hydroxylase gene family: identification of type II P-450(15)alpha as coumarin 7-hydroxylase

Biochemistry. 1989 May 16;28(10):4169-72. doi: 10.1021/bi00436a007.


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).

MeSH terms

  • Animals
  • Aryl Hydrocarbon Hydroxylases*
  • Cytochrome P-450 CYP2A6
  • Cytochrome P-450 Enzyme System / genetics*
  • Cytochrome P-450 Enzyme System / metabolism
  • Cytochrome P450 Family 2
  • DNA / genetics
  • Enzyme Induction / drug effects
  • Female
  • Gene Expression Regulation
  • Male
  • Mice
  • Mixed Function Oxygenases / genetics*
  • Mixed Function Oxygenases / metabolism
  • Multigene Family
  • Pyrazoles / pharmacology
  • Steroid Hydroxylases / genetics*
  • Steroid Hydroxylases / metabolism


  • Pyrazoles
  • pyrazole
  • DNA
  • Cytochrome P-450 Enzyme System
  • Mixed Function Oxygenases
  • Steroid Hydroxylases
  • Aryl Hydrocarbon Hydroxylases
  • Cyp2a4 protein, mouse
  • Cytochrome P-450 CYP2A6
  • Cytochrome P450 Family 2
  • steroid 15-alpha-hydroxylase