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-450b/e in rat liver. By screening a human liver cDNA library in bacteriophage lambda gt11, 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(1), HLp, P-450NF, P1-450 4, and P3(450), but the nucleotide sequence of pHY13 is 80% similar to the reported sequence of rat cytochrome P-450, P-450(M-1). 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-450MP, 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-450MP, and may belong to the category of developmentally regulated constitutive cytochrome P-450s.

Expression of a human liver cytochrome P-450 protein with tolbutamide hydroxylase activity in Saccharomyces cerevisiae

“…However, in this laboratory only three distinct cDNA clones have been isolated from a human library (constructed from a single liver) by using antisera or oligonucleotide probes related to P-45oMp (Umbenhauer et al, 1987;Ged et al, 1988) (MP-12 is very closely related to MP-20 and might not be a distinct gene product). Other laboratories have reported the isolation of one or more of these three clones (Kimura et al, 1987a;Okino et al, 1987;Yasumori et al, 1987), but additional clones have not been identified. The MP-20 clone appears to encode P-45oMp-3, which apparently has neither mephenytoin, hexobarbital, nor tolbutamide hydroxylase activity (Ged et al, 1988).…”

Cytochrome P4502C9: an enzyme of major importance in human drug metabolism

“…As noted earlier, six different CYP2C9 sequences have been identified to date, with another sequence, CYP2C10 , originally being classified separately due to differences in the 3′–untranslated region [8, 9, 12–17]. Nine nucleotide substitutions in the coding region of CYP2C9 account for the various sequences reported.…”

“…CYP2C9 protein has been purified from human liver [10, 11] and a number of variant CYP2C9 cDNAs have been isolated [8, 9, 12–17]. The deduced amino acid sequences of the CYP2C9 variants differ at only a few residues; the significance of the existence of allelic variants on CYP2C9 activity is discussed under ‘Pharmacogenetics’.…”

Characterization of Human Microsomal Cytochrome P-450 Enzymes

“…Recently a nearly identical clone, containing only a six-base deletion in the coding sequence, has been isolated from another cDNA library by Komori et al (71). The isolation of a second cDNA clone, MP-4, from the same cDNA library as MP-8, shows only two (non-silent) base differences in the protein coding region from the MP-8 clone, but differs dramatically in the 3' nontranslated region (23); what appears to be essentially the same clone (2 base differences) has been isolated from another library by Yasumori et al (100). The N-terminal sequences predicted by the MP-4 and MP-8 cDNA clones match those determined by amino acid sequencing of both the P-450MP_1 and P-450MP_2 proteins (89).…”