Identification and nucleotide sequence of the leukocyte and reticulocyte forms of rabbit cytochrome b5 mRNA

RNA extracted from rabbit leukocytes and reticulocytes was reverse transcribed and used in the Polymerase Chain Reaction technique along with primers designed to amplify the coding sequence of rabbit cytochrome b5. The resultant amplified products were subcloned and analyzed. Sequencing confirmed that leukocyte and liver cDNAs are homologous and encode the membrane-bound form of the protein. In contrast, reticulocytes exhibit a highly similar, but different mRNA which encodes the smaller, soluble cytochrome b5. This is the first example of a cytochrome b5 sequence from a tissue other than liver, erythrocyte or reticulocyte.