Chapter 15, Problem 21P

Interpretation Introduction

To Suggest:

Reactions by which the reversibility of glycogen phosphorylate from a form to b form when hormone disappears should be suggested.

Introduction:

Glycogen phosphorylase has two forms as less active b form and more active a form. Glycogen phosphorylase can be activated via an enzyme cascade. First adenylyl cyclase which is a membrane bound enzyme that converts ATP to cAMP, is stimulated by a hormone. cAMP is a signaling molecule found in all eukaryotic cells. Cyclic AMP activates cAMP dependent protein kinase and induces a conformational change. This activated cAMP protein kinase can phosphorylate other proteins like phosphorylase kinase. Phosphorylase kinase is inactive in unphosphorylated state and active in phosphorylated form. The activated phosphorylase kinase, then phosporylates glycogen phosphorylase. This results in the conversion of less active glycogen phosphorylase form b into more active form a.