Question

Glycogen phosphorylase

Allosteric effectors - in skeletal muscle
1. Phosphorylase (a/b) form is responsive to energy charge (ATP vs. AMP):
a. Phosphorylase (answer 1) in muscle (active/inactive) during rest, (active/inactive) during exercise
b. (ATP/AMP) (signals low E charge) is allosteric activator
(ATP/AMP) (signals high E charge) and ___________ are allosteric inhibitors.

Answer 1

Glycogen phosphorylase in skeletal muscle is active during exercise and inactive during rest. AMP is an allosteric activator of phosphorylase, signaling low energy charge, while ATP is an allosteric inhibitor of phosphorylase, signaling high energy charge.

Step-by-step explanation:

Glycogen phosphorylase is an enzyme involved in glycogenolysis, the breakdown of glycogen into glucose. It exists in two forms: phosphorylase a (active) and phosphorylase b (inactive). The activity of phosphorylase in skeletal muscle is regulated by the energy charge of the cell, which is determined by the ratios of ATP and AMP. During rest, when the energy charge is high, phosphorylase is inactive. During exercise, when the energy charge is low, phosphorylase is active. AMP, which signals low energy charge, is an allosteric activator of phosphorylase, while ATP, which signals high energy charge, is an allosteric inhibitor of phosphorylase.