Reaction of the futile cycle:-
A) An adequate level of cAMP stimulates formation of the inactive 'D' form of glycogen synthase and the active form of phosphorylase. Thus, glycogenesis is limited and glycogenolysis is increased.
B) With a low level of CAMP, the active I form of glycogen synthase predominates and the active form of phosphorylase kinase is low because the common phosphorylating enzyme, cAMP dependent protein kinase, is inactive. There, glycogenesis is increased and glycogenolysis is decreased.