Assignment of amides in the amino acid sequence of mammalian calmodulin by mass spectrometry

The primary structure of mammalian calmodulin from various sources was analyzed by secondary ion mass spectrometry. The assignments of amide groups at residues 24, 60, 129 and 135, which had been controversial in the previous reports, were in perfect agreement with the amino acid sequence deduced from the cDNA sequence of calmodulin of other vertebrates. The result is against the post-translational amidation or deamidation process of this protein.