Nucleotide Sequence of a Human Liver Cytochrome P-450 Related to the Rat Male Specific Form1

Abstract

P-450 human-2 is a human cytochrome P-450 that is immunochemicaLly related to a constitutive male-specific cytochrome P-450 (P-450-male) and the phenobarbital-inducible P-45Ob/e in rat liver. By screening a human liver cDNA library in bac-teriophage λgtll, we isolated a clone with an insert length of 1,847 bases (pHY13). The clone was sequenced and shown to code for a protein of 487 amino acids. The N-terminal 11-amino-acid sequence was in agreement with the protein sequence of P-450 human-2. The nucleotide sequence of pHY13 showed less than 50 % similarity with those of human cytochrome P-450s, pHP-450(l), HL_P, P-450_NF, P₁-450, P-450 4, and P₃450, but the nucleotide sequence of pHY13 is 80% similar to the reported sequence of rat cytochrome P-450, P-450(M-l). In addition, the coding sequence of pHY13 showed close similarity to that of MP-8, which was recently reported as the sequence corresponding to human cytochrome P-450_MP, although no apparent similarity was observed in their 3′ non-coding sequences except for the first 75 bases and the expected length of the complete sequences. These results, together with the immunochemical data, indicate that P-450 human-2 is closely related, but not identical, to P-450_MP, and may belong to the category of developmentally regulated constitutive cytochrome P-450s.