Determination of the phosphorylation sites of calmodulin catalyzed by casein kinase 2.
Calmodulin is specifically phosphorylated by casein kinase 2 (CK 2), but not by casein kinase 1, A kinase, or C kinase. In the present report, the stoichiometry of the phosphorylation of calmodulin by CK 2 in the presence and absence of polylysine and its phosphorylation sites were examined. In the absence of polylysine, the radioactive phosphate incorporated into calmodulin by CK 2 was only 0.01 mol/mol and the phosphorylation occurred at Ser-101. In the presence of polylysine, 1.2 mol of radioactive phosphate was incorporated into 1 mol of calmodulin. In this case, Thr-79 in addition to Ser-101 was phosphorylated, but Ser-81 was not. The sequence around the phosphorylated Thr is Asp-Thr(P)-Asp-Ser-Glu-Glu-Glu-.
Nakajo
S
S
Laboratory of Biological Chemistry, School of Pharmaceutical Sciences, Showa University, Tokyo.
Masuda
Y
Y
Nakaya
K
K
Nakamura
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002147:Calmodulin / Q000378:metabolism*; D047388:Casein Kinases; D066298:In Vitro Techniques; D007700:Kinetics; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011107:Polylysine / Q000494:pharmacology; D011494:Protein Kinases / Q000378:metabolism*; D013379:Substrate Specificity
D002147:Calmodulin; D011107:Polylysine; D011494:Protein Kinases; D047388:Casein Kinases