In exercising muscle, glycogen degradation supplies the muscle with glucose 6-ph
ID: 858811 • Letter: I
Question
In exercising muscle, glycogen degradation supplies the muscle with glucose 6-phosphate. In order to stimulate muscle glycogen degradation, protein phosphatase 1 (PP1) must be inhibited. Four of the following five events are involved in the inactivation of PP1 in exercising muscle. Which event is not involved?
- Epinephrine initiates a cAMP signal transduction cascade that utilizes protein kinase A.
- Phosphorylated PP1 inhibitor binds to PP1, facilitating glycogen degradation by phosphorylase a.
- Insulin initiates a protein kinase cascade that utilizes glycogen synthase kinase.
- Protein kinase A phosphorylates GM in the GM-PP1 complex, resulting in its dissociation.
- Protein kinase A phosphorylates an inhibitor of PP1.
Explanation / Answer
The following event not involved:
Insulin initiates a protein kinase cascade that utilizes glycogen synthase kinase.