Glycogen synthase kinase-3 (ATP: protein phosphotransferase, EC 188.8.131.52) phosphorylated K-casein 20-fold more rapidly than β-casein, while αS1-casein was not a substrate. This distinguished it from casein kinase-I and casein kinase-II, which phosphorylate the β-casein variant preferentially. Glycogen synthase kinase-3 phosphorylated a serine residue(s) in the C-terminal cyanogen bromide fragment on K-casein. In contrast, cyclic AMP-dependent protein kinase phosporylated the N-terminal fragment, and phosphorylase kinase the N-terminal and intermediate cyanogen bromide fragments. The results emphasize the potential value of casein phosphorylation as a means of classifying protein kinases.
|Number of pages||5|
|Journal||Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular|
|Publication status||Published - 15 Jun 1983|
- (Rabbit skeletal muscle)
- Casein kinase
- Glycogen synthase kinase
- Protein kinase