Question

Identify the true statements regarding liver glycogen phosphorylase a. Protein phosphatase 1 is abbreviated PP1. The binding of glucose to liver phosphorylase a shifts the equilibrium from the active form to the inactive form. Liver phosphorylase a concentration decreases when glucose enters the blood. As the concentration of phosphorylase a decreases, the activity of glycogen synthase increases. Liver phosphorylase a is regulated by AMP, adenosine monophosphate. When PP1 is bound to phosphorylase a, both PP1 and phosphorylase a are active.

Answer 1

Answer:

Liver phosphorylase a concentration decreases when glucose enters the blood.

The binding of glucose to liver phosphorylase a shifts the equilibrium from the active form

As the concentration of phosphorylase a decreases, the activity of glycogen synthase increases. to the inactive form

Explanation:

Protein phosphatase 1 (PP1) is a phosphatase enzyme known to remove phosphate groups from serine/threonine amino acid residues. PP1 plays diverse biological roles including, among others, cell progression, control of glucose metabolism, muscle contraction, etc. In glucose metabolism, PP1 regulates diverse glycogen metabolizing enzymes (e.g., glycogen synthase, glycogen phosphorylase, etc). In the liver, glycogen phosphorylase catalyzes the rate-limiting step in glycogenolysis by releasing glucose-1-phosphate. Glycogen phosphorylase a is converted (and inactivated) into the b form by PP1, which catalyzes the hydrolysis of the phosphate bond between serine and the phosphoryl group. In the liver, glucose binds in order to inhibit glycogen phosphorylase a, thereby inducing the dissociation and activation of PP1 from glycogen phosphorylase a.