Isolation and characterization of the rabbit cytochrome b5 gene

The nucleotide sequence data reported in this paper will appear in the GSDB, DDBJ, EMBL and NCBl nucleotide sequence databases with the following accession number D38567, D38568, D38569, D38570 and D38571. In mammals, two forms of cytochrome b5 (b5) are present and they are called according to their subcellar distribution as the microsomal-form and the soluble-form. These two forms of b s were encoded by separate mRNAs. In order to elucidate the mechanism of the expression of these two mRNAs, we isolated genomic clones that cover the gene for b from the rabbit genomic library. Analysis of these clones revealed that b5 gene spans over 20kbase pairs. A solube-form specific exon was found to be present between the two exons, which are in common to both forms of b5s. These observation demonstrate that the two forms of b5 mRNA are derived from the same gene by the alternative exon skip splicing.