DIFFERENCES IN PROTEIN-PHOSPHORYLATION INVIVO AND INVITRO BETWEEN WILD-TYPE AND DUNCE MUTANT STRAINS OF DROSOPHILA-MELANOGASTER

The protein phosphorylation patterns of wild type and dunce mutant strains of D. melanogaster, as detected by sodium dodecylsulfate-gel electrophoresis and autoradiography, were compared. After labeling in vivo with 32Pi or in vitro in homogenates with [.gamma.-32P]ATP, radioactive bands at and above apparent polypeptide MW .apprx. 110,000 were more pronounced in dunce fly heads than in wild type heads. When labeling in vitro, in dunceM11 there appeared a radioactive band at apparent MW .apprx. 53,000 that was faintly visible in the wild strain. The same band could be intensified in both strains by adding cAMP to the homogenate or by performing homogenization in the presence of theophylline. The MW .apprx. 53,000 protein is a substrate for cAMP-dependent protein kinase.