25.1 Glycogen Is Synthesized and Degraded by Different Pathways
Glycogen is synthesized by a different pathway from that of glycogen breakdown. UDP-
25.2 Metabolism in Context: Glycogen Breakdown and Synthesis Are Reciprocally Regulated
Glycogen synthesis and degradation are coordinated by several amplifying reaction cascades. Epinephrine and glucagon stimulate glycogen breakdown and inhibit its synthesis by increasing the cytoplasmic concentration of cAMP, which activates protein kinase A. Protein kinase A activates glycogen breakdown by attaching a phosphoryl group to phosphorylase kinase and inhibits glycogen synthesis by phosphorylating glycogen synthase.
The glycogen-