Glycogen Metabolism II

Question 1

insulin

Answer 1

activates a protein phosphatase which removes a phosphate from glycogen synthase and glycogen phosphorylase

Question 2

de-phosphorylated glycogen synthase

Answer 2

activated to make glycogen

Question 3

de-phosphorylated glycogen phosphorylase

Answer 3

deactivated

Question 4

glucagon

Answer 4

activates cAMP which phosphorylates glycogen synthase and glycogen phosphorylase

Question 5

phosphorylated glycogen synthase

Answer 5

deactivated

Question 6

phosphorylated glycogen phosphorylase

Answer 6

activated to break glycogen alpha-1,4 linkages, releasing glucose-1-P

Question 7

glycogenolysis

Answer 7

glycogen phosphorylase is activated and glycogen synthase is inhibited; glycogen broken down

Question 8

phosphorylase b

Answer 8

inactive form of glycogen phosphorylase; de-phosphorylated

Question 9

phosphorylase a

Answer 9

active form of glycogen phosphorylase; phosphorylated

Question 10

What activates glycogen phosphorylase?

Answer 10

glucagon, AMP, and epinephrine

Question 11

What deactivates glycogen phosphorylase?

Answer 11

insulin, glucose, ATP, glucose-6-P

Question 12

activation of muscle glycogen phosphorylase

Answer 12

Ca++ release from muscle contraction (allosteric) and epinephrine release (hormonal) will both activate calmodulin and ultimately phosphorylase kinase which will phosphorylate glycogen phosphorylase for activation

Question 13

inhibition of muscle glycogen phosphorylase

Answer 13

myosin ATPase will activate adenylate cyclase to dephosphorylate glycogen phosphorylase

Question 14

epinephrine

Answer 14

will bind alpha-1 adrenergic receptors to induce release of Ca++ and induce phosphorylation of glycogen synthase (inactive) by calmodulin-dependent kinase and PKC

Question 15

PKA

Answer 15

activates phosphorylase kinase and activates the protein phosphatase 1 inhibitor (PP1) –> glycogen synthase will be inactivated by phosphorylation

Question 16

inhibition of protein phosphatase inhibitor

Answer 16

prolongs glycogenolysis

Question 17

PP1 activation

Answer 17

will dephosphorylate phosphorylase kinase and glycogen phosphorylase, inhibiting glycogenolysis –> dephosphorylates glycogen synthase for activation

Question 18

glycogenesis

Answer 18

activation of glycogen synthase and inhibition of glycogen phosphorylase

Question 19

glucose-6-P

Answer 19

activates glycogen synthase in both muscle and liver

Question 20

insulin mode of action

Answer 20

will activate the phosphodiesterase that converts cAMP to AMP (no PKC for phosphorylation) and inhibits glycogen synthase kinase 3 (will phosphorylate glycogen synthase to inactive it); will also phosphorylate regulatory subunit of PP1 to increase its affinity for glycogen synthase

Question 21

glycogen storage disease IXa

Answer 21

phosphorylase kinase deficiency

Question 22

phosphorylase kinase deficiency

Answer 22

affects liver; results in hepatomegaly, hypoglycemia, and short stature