glycogen dynamics

Question 1

T/F: muscle glycogen helps keep blood glucose concentrations around 90 mg/dl

Answer 1

False. Muscle glycogen does not contribute to blood glucose concentrations. Muscle glycogen stores are a rapidly mobilizable store of glucose for mechanical energy generation by muscle.

Question 2

what enzyme is responsible for elongation of glycogen making alpha 1-4 bonds at non-reducing ends?

Answer 2

glycogen synthase

Question 3

what protein is intrinsic to “seeding” glycogen synthesis?

Answer 3

glycogenin

Question 4

summarize the mechanism of action of glucagon

Answer 4

• *remember that there are no glucagon receptors in muscle:
  1. Binding to extracellular portion of receptor located on the cytoplasmic membrane
  2. G‐protein mediated signal transduction cascade activated
  3. Adenylyl‐cyclase enzyme activated
  4. cAMP levels increase
  5. Protein kinase A activated
  6. Target proteins phosphorylated

Glycogen synthase is inhibited. Phosphorylase kinase is activated, so phosphorylase is phosphorylated and
thereby activated.