Polycation-dependent, Ca2+-antagonized phosphorylation of calmodulin by casein kinase-2 and a spleen tyrosine protein kinase.
Ten distinct protein kinases have been tested for their ability to phosphorylate calmodulin. Only casein kinase-2 and a spleen tyrosine protein kinase (TPK-III) proved effective, their phosphorylation efficiency being dramatically enhanced by histones and other polybasic peptides while being depressed by 50 microM Ca2+. Phosphorylation by CK-2 takes place with a Km of 12 microM calmodulin, leading to the incorporation of more than 1.5 mol P/mol substrate. Ser81 and Thr79 are among the residues affected. On the other hand, the two tyrosyl residues of calmodulin are both phosphorylated by TPK-III, Tyr99 being preferred over Tyr138.
Meggio
F
F
Brunati
A M
AM
Pinna
L A
LA
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000378:metabolism*; D047388:Casein Kinases; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D013154:Spleen / Q000201:enzymology; D013997:Time Factors
D002147:Calmodulin; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D047388:Casein Kinases; D002118:Calcium