CDNA CLONING AND EXPRESSION OF A NOVEL CYP3A FROM THE SYRIAN-HAMSTER,CYP3A31

A clone, encoding a cytochrome P450 protein consisting of 501 amino ac ids, was isolated from a cDNA library constructed from mRNA of Syrian hamster liver. The deduced amino acid sequence of this clone showed a high homology (65 to 81%) with other mammalian CYP3As and hence, this novel isozyme was named CYP3A31. By Northern blotting, using an oligon ucleotide specific to CYP3A31, the mRNA for this isozyme was shown to be expressed constitutively in liver and induced by treatment with phe nobarbital but repressed by 3-methylcholanthrene or dexamethasone trea tments. The increase in mRNA expression by phenobarbital and decrease by dexamethasone corresponded to changes in CYP3A protein as analysed by Western blotting. These indicate that CYP3A31 might constitute one of the major CYP3A isozymes in the hamster. (C) 1998 Elsevier Science B.V.