ALTERNATIVE SPLICING OF CYTOCHROME P4502B2 MESSENGER-RNA IN RAT-LIVER

The possibility of alternative splicing of the cytochrome P4502B2 mRNA was studied in the liver of rats treated with various inducers: pheno barbital, pyridine, and Arochlor 1254. The CYP2B2 cDNA prepared by rev erse transcription with specific primers was amplified with the primer s allowing discrimination of mRNA products of normal and alternative s plicing. The two mRNA variants were found in the liver of both control and induced animals, which proves the P4502B2 mRNA alternative splici ng in the rat liver to occur independently of the inductors studied. I mmunoblotting assay (anti-CYP2B1/B2 antibodies) of CYP2B2 proteins in liver microsomes of the rats treated with phenobarbital, pyridine, or Arochlor 1254 showed that pyridine and Arochlor 1254 do not induce, in liver microsomes, the synthesis of CYP2B1 or CYP2B2 nor of a protein immunochemically related to CYP2B (CYP2Bx) with molecular mass exceedi ng that of CYP2B2. Absence of CYP2Bx in the control and phenobarbital- treated microsomes demonstrates that there is no perspicuous relation between CYP2Bx presence and the mRNA resulting from alternative splici ng.