Phosphorylation of calmodulin by the epidermal-growth-factor-receptor tyrosine kinase.
An epidermal-growth-factor(EGF)-receptor preparation isolated by calmodulin-affinity chromatography from rat liver plasma membranes is able to phosphorylate calmodulin. Calmodulin phosphorylation was enhanced 3-8-fold by EGF, was dependent on the presence of a polycation or basic protein and was inhibited by micromolar concentrations of Ca2+. Phosphate incorporation into calmodulin occurs predominantly on tyrosine residues. Partial proteolysis of phosphocalmodulin by thrombin identifies Tyr99, located in the third calcium-binding domain of calmodulin, as the phosphorylated residue. Stoichiometric measurements show a 32P/calmodulin molar ratio of approximately 1 when optimal phosphorylation conditions are used.
Benguría
A
A
Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
Hernández-Perera
O
O
Martínez-Pastor
M T
MT
Sacks
D B
DB
Villalobo
A
A
D000818:Animals; D002147:Calmodulin / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D066246:ErbB Receptors / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D008297:Male; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley
D002147:Calmodulin; D066246:ErbB Receptors