Muscle contraction is associated with elevated levels of cytosolic calcium. Which statement describes a consequence of this increase in calcium?
A) Calcium is a divalent cation, which binds to ATP and reduces electrostatic repulsion between the phosphates. Glycogen is broken down to compensate for the decreased energy available from ATP hydrolysis.
B) An increased level of calcium is associated with an increase in glycogen breakdown, as calcium is an allosteric activator of glycogen phosphorylase.
C) Calcium activates phosphoprotein phosphatase 1, which in turn will stimulate glycogen synthesis by dephosphorylating phosphorylase b.
D) An increased level of calcium is associated with an increase in glycogen breakdown, as calcium is an allosteric activator of phosphorylase b kinase.
E) All the answers are correct.

Question

Quizplus · Accepted Answer

An increase in cytosolic calcium is associated with an increase in glycogen breakdown, as calcium is an allosteric activator of phosphorylase b kinase. This activation leads to the conversion of phosphorylase b to phosphorylase a, which can then break down glycogen into glucose-1-phosphate. Choices A, B, and C are incorrect as they do not accurately describe the role of calcium in glycogen metabolism.

Muscle Contraction Is Associated with Elevated Levels of Cytosolic Calcium