Characterisation of calmodulin from Drosophila heads

Calmodulin from Drosophila heads has been purified to apparent electrophoretic homogeneity. It has the same characteristics as bovine brain calmodulin with respect to the migration upon polyacrylamide gel electrophoresis and maximal activation of a calmodulin-deficient cAMP phosphodiesterase. The amino acid composition resembles bovine brain calmodulin with the exception that trimethyllysine is absent and that it contains only one tyrosine. The tryptic peptide map of Drosophila calmodulin suggests some differences in the amino acid sequence as compared to bovine brain calmodulin. These proposed differences in the primary structure may explain why Drosophila calmodulin is less potent than bovine brain calmodulin in the activation of a cAMP phosphodiesterase from bovine brain.