The synthesis and degradation of glycogen provide control of the availability of phosphatases keeps phosphorylase inactive and activates glycogen synthase. Glycogen synthesis is inactivated by phosphorylation of glycogen synthase, the enzyme responsible for making glycogen.
Regulation of glycogen synthesis and degradation is essentially the same in the liver and muscle, but there are a couple of wrinkles. Glycogen degradation is also activated in muscle in response to the rise in intracellular calcium levels that accompanies contraction. This is achieved by