Question

Summarize the effects of phosphorylation and dephosphorylation on glycogen phosphorylase and glycogen synthase.

Short answer

The glycogen phosphorylase is activated by the process of phosphorylation, whereas glycogen synthase is inactivated by process of phosphorylation.

On the other hand, de-phosphorylation inactivates glycogen phosphorylase and activates glycogen synthase.

Step-by-step solution

Why does one activity get  activated while the other get deactivated by phosphorylation?

It is because of the fact that the correlation between phosphorylation and enzyme activity varies with the enzyme.The phosphorylation confers the glycogen phosphorylase into a more stable conformation whereas glycogen synthase is converted to a less active conformation. This result in inhibition of glycogen synthase.

The glycogen phosphorylase interconvertible enzyme system.

Conversion of phosphorylase b which is known to be the less active form to phosphorylase-a which is the more active form is achieved through phosphorylation which is catalyzed by phosphorylase kinase.