The control of enzyme activity involves covalent modifications, including the addition of phosphate ions to serine, threonine and tyrosine residues in the enzyme. This addition is catalysed by protein kinases. The reverse reaction is carried out by phosphatase.
Effects of activation of phosphoprotein phosphatase
This leads to phosphorylase kinase and glycogen phosphorylase's becoming inactive, while glycogen synthase is activated. As a result, glycogen synthesis is increased and glycogenolysis is decreased, and the net effect is for energy to enter and be stored inside the cell.