Lacroix D, Desrochers M, Lambert M, Anderson A
Centre de Recherche en Cancérologie de l'Université Laval, L'Hôtel-Dieu de Québec, Canada.
Gene. 1990 Feb 14;86(2):201-7. doi: 10.1016/0378-1119(90)90280-5.
Cytochrome P450e (P450IIB2) is a phenobarbital(PB)-inducible member of the rat liver P450IIB subfamily. Among P450 cDNA clones previously isolated from a cDNA library made from the liver of a single rat were several that contained P450e inserts, including PB13, PB16, and PB22. By nucleotide sequence analysis, the PB16 and PB22 inserts have now been found to contain an additional 24-bp segment not present in the PB13 insert or in previously reported P450e-coding sequences. According to the published P450e genomic sequence, the 24-bp segment is exactly at the junction of the fifth and the sixth exons and its sequence is identical to the first 24 bp of the fifth intron. Translation of this segment would add 8 amino acid residues to the P450e protein. To detect the alternatively spliced P450e mRNA, a synthetic oligodeoxyribonucleotide (oligo) corresponding to 18 of the 24 bp of the intronic sequence found in the PB16 and PB22 inserts was made. This oligo hybridized with a 2.1-kb RNA on Northern blots of liver RNA from PB- or Aroclor 1254-treated rats. Taken together, these results indicate that individual rats can possess both forms of P450e mRNA and that an alternative splicing mechanism is responsible for their formation.
