since the presence of ca2+ in the cell culture medium was essential for the phosphorylation of the 18,000 mol . wt protein and , since trifluoperazine ( a potent inhibitor of calmodulin as well as of the degranulation process of rbl-2h3 cells ) inhibited the reaction , the phosphorylation may be catalyzed by a ca2+-calmodulin-dependent process , most likely by myosin light chain kinase .
C0031715
phosphorylation
C0027120
myosin light chain kinase