Characterization of rabbit cytochrome P450IIC4 cDNA and induction by phenobarbital of related hepatic mRNA levels.

We have cloned cDNA containing a partial sequence of a rabbit cytochrome P-450 (designated cytochrome P450IIC4) cDNA that is a member of the cytochrome P450IIC subfamily. The cDNA contains 770 bp of which the first 429 code for the C-terminal 143 amino acids of cytochrome P450IIC4. The protein coding region of the cDNA is 98% homologous with that of cytochrome P450IIC5 and the 3' untranslated region is about 90% homologous. In contrast to the constitutive isozyme, cytochrome P450IIC5, mRNA in the liver that hybridized to the 3' untranslated region of cytochrome P450IIC4 cDNA was increased about 8-fold 24 hours after a single injection of phenobarbital.