IDENTIFICATION OF CYP2B14P AND CYP2B16P, 2 APPARENT PSEUDOGENES IN THE RAT CYTOCHROME-P450 2B (CYP2B) SUBFAMILY

Cytochrome P450 2B3 (CYP2B3) is a member of the CYP2B subfamily and is present constitutively in rat liver. During cloning of the CYP2B3 gen e, several variant genomic inserts were isolated, exon-containing frag ments of which were identified by hybridizing to CYP2B3 cDNA or exonic probes. Nucleotide sequence analysis of one set of variant inserts sh owed them to carry exon 1 and the 5'-flanking region of a gene designa ted CYP2B14P. The last codon of CYP2B14P exon 1 is a TAG translation s top codon, and thus CYP2B14P is a pseudogene. Three other inserts cove ring 34 kb of genomic sequence together carried 9 exons and the 5'- an d 3'-flanking regions of the gene designated CYP2B16P. The 5'-splice s ite of CYP2B16P intron 1 is inactivated by the replacement of G by T i n the normally invariant GT dinucleotide. Thus, CYP2B16P also has the characteristics of a pseudogene. The identification of CYP2B14P and CY P2B16P brings to at least seven the number of genes or pseudogenes sho wn by nucleotide sequence analysis to belong to the rat CYP2B subfamil y.