The isolation and characterization of the bovine cytochrome b5 gene, and a transcribed pseudogene

This is the first isolation and characterization of a cytochrome b5(b5) gene. The bovine b5 gene is quite large, spanning about 28 kb and contains six exons. One of these exons appears to code for a reticulocyte-specific sequence similar to that described for human and rabbit b5. All of the splicing junctions conform to the GT-AG consensus rule. The 5' flanking sequence has no obvious TATA box, two CAAT boxes, and contains several G:C-rich SpI motifs indicative of a house-keeping gene. In reticulocyte mRNA we found evidence for a transcribed b5 pseudogene, but could not detect sequences coding for the soluble form of b5. We conclude that the soluble form of b5 is derived from the membrane-bound b5 by a post-translational mechanism.