Factors affecting muscle glycogen synthetase activity. IV. Comparative study of the different dependent forms of glycogen synthetase.

The properties of the glucose 6-phosphate-dependent forms of glycogen synthetase obtained by incubation with calcium ions or with adenosine triphosphate were compared. The two preparations showed different sensitivity to the action of heat and trypsin. In addition, the synthetase obtained with adenosine triphosphate is reconvertible to the independent form while that prepared with Ca++ is not. The possible physiological role of the two different mechanisms of formation of the glucose 6-phosphate-dependent forms of glycogen synthetase is discussed.