Glycogen phosphorylase and glycogen synthase
A) are not activated simultaneously
B) are activated simultaneously under special circumstances
C) can be activated simultaneously under any circumstances
D) are involved in catalysis of the same process

Question

Quizplus · Accepted Answer

Glycogen phosphorylase and glycogen synthase are not activated simultaneously because they serve opposing functions in glycogen metabolism. Glycogen phosphorylase breaks down glycogen into glucose-1-phosphate, while glycogen synthase is responsible for the synthesis of glycogen from glucose. Their activities are regulated in a reciprocal manner to ensure that breakdown and synthesis of glycogen do not occur at the same time, which would be energetically wasteful.

Glycogen Phosphorylase and Glycogen Synthase