Answer:
One of the essential post-translational regulatory mechanisms, which can influence the stability, activity, or localization of a protein is phosphorylation.
a) The phosphorylation of glycogen phosphorylase takes place by phosphorylase kinase. After phosphorylation, the glycogen phosphorylase gets stimulated and mediates the process of glycogenolysis. In case, if a mutation occurs in the phosphorylase kinase gene, the activation of glycogen phosphorylase cannot take place, and as consequence glycogenolysis will fail to take place.
b) The phosphorylation of glycogen synthase takes place by protein kinase A, also known as glycogen synthase kinase 3. After phosphorylation, the glycogen synthase becomes inactive and thus fails to mediate the process of glycogen biosynthesis. In case, if a mutation takes place in the protein kinase gene, the glycogen synthase enzyme will remain active all the time, and as a consequence, the process of glycogen biosynthesis takes place spontaneously.
