Interaction of calmodulin and glycogen phosphorylase

We have demonstrated the interaction of 125I-labeled calmodulin with glycogen phosphorylase by four techniques: polyacrylamide gel overlay, sucrose density centrifugation, gel filtration chromatography, and affinity chromatography. Phosphorylase b has more affinity for calmodulin than does phosphorylase a. Under all conditions tested, the presence of calmodulin affects neither the enzymatic activity nor any kinetic characteristics of phosphorylase a or b. We present these results as evidence that while binding between calmodulin and phosphorylase clearly exists, it may not have a physiological role.