Calmodulin, which was originally reported as a Ca2+ dependent activator of phosphodiesterase, mediates a number of actions of Ca2+ as a second messenger for stimulus linked cellular responces in eukaryotic cells. In blood platelets, the availability of Ca2+is a prerequisite for steps of platelet reaction leading to the formation of hemostatic plug. The presence of this protein in platelets has been reported. In the present study, calmodulin was purified from bovine platelets and was extensively characterized.The identification of the protein was based on the activity to activate the brain calmodulin deficient phosphodiesterase. Calmodulin was purified 600 fold from bovine platelet pellet by a 3-step purification method consisted of trichloroacetic acid treatment, DEAE-cellulose column chromatography and phenothiazine affinity chromatography. The recovery rate was more than 70% and the purified protein was homogenous on polyacrylamide gel electrophoresis. The mobility of the purified material upon polyacrylamide gel electrophoresis was identical with that of brain calmodulin in the presence of either Ca2+or EGTA. In the quantitative analysis of the phosphodiesterase activation, the behaviour of the purified protein was also identical with brain calmodulin.From these strict characterization, it may be concluded that the purified protein is indistinguishable from brain calmodulin. The amount of the protein in bovine platelet was estimated to be 63 micrograms per wet gram, which is about one sixth of the amount in brain tissue.
Characterization of Sm14 related components in different helminths by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blotting analysis
