Isolation and characterization of the Bos tuurus I-casein gene (Milk proteins; intron; exon; promoter; cr recombinant DNA; bovine genome)

SUMMARY The expression of casein genes in the mammary cells is regulated by peptide and steroid hormones. To investigate the controlling mechanisms we have isolated and characterized the bovine /?-casein gene. The gene has the size of 8.6 kb, which is 7.8 times longer than the corresponding mRNA composed of nine exons. The genomic clones include additional 8.5kb and 4.5-kb sequences of the 5’- and 3’-flanking regions. We have determined the sequences of the 5’ and 3’ ends of the gene and compared them with the respective sequences of the rat /?-casein gene. Conserved sequences are identical or homologous to the potential binding sites for nuclear factors and for glucocorticoid and progesterone receptors. The regulatory region contains two different TATA signals and a repeat sequence between them.