The amino acid sequence of the phosphorylase kinase delta subunit has been determined using cyanogen bromide peptides. These peptides were ordered by isolation of the tryptic peptides containing carboxyl[14C]methylmethionine. The protein is identical to bovine uterus calmodulin and differs from bovine brain calmodulin only in amide assignments. The delta subunit contains 148 amino acids, including one residue of trimethyllysine, and has a molecular weight of 16680. The N terminus is blocked, probably with an acetyl group, and the protein has a net overall charge at pH 7 of -24. The asparagine residues 60 and 97 have been shown to be partially deamidated in the protein. The sequence of the N-terminal tripeptide and the amide assignments on residues 58 and 60 were not determined unequivocally.