Nucleotide sequence of a cDNA encoding mouse beta casein.

Beta casein 1s a major «1 Ik protein produced by the lactating mammary gland and I t s gene expression 1s hormonally controlled ( 1 ) . cDKAs encoding mouse beta casein wore Isolated from a muse maoaary gland l ibrary prepared as described ( 2 ) , using a short cONA clona of mouse beta casein (1) as a hybridization probe. The longest cDNA clone was chossn and the DNA sequence of each strand was detorained by the chain termination nethod [ 3 ) . Templates for sequencing were prepared by either delation (4) or Hu phege Insertion (K. Mizuuchi, personal communication). The sequence of 1120 bp minus the polyA t a l l 1s presented below with the deduced ami no add sequence. The nucleotide sequence Includes 55 bp of the 5'-untranslated region, the 693 bp coding region and 372 bp of the 3'-untranslated region. Comparison of our data with those reported for rat beta casein (5) revealed 66% homo Logy at the nucleotide level and 78% homo logy at the emino add level , which Includes 100* horology at the 15 aalno acid residues of signal peptide.