Glycogen Degradation

Question 1

What are the steps of Glycogen Breakdown (Glycogenolysis)?

Answer 1

1. Phosphorylation of Glycogen
2. Debranching of Glycogen
3. Conversion of Glucose-1-Phosphate to Glucose-6-Phosphate
4. (OPTIONAL) conversion of Glucose-6-Phosphate to Free Glucose

Question 2

What are the enzymes of Glycogen Breakdown (Glycogenolysis)?

Answer 2

1. Glycogen Phosphorylase
2. Debranching Enzyme (transferase and α-1,6-glucosidase)
3. Phosphoglucomutase
4. Glucose-6-Phosphatase, Liver Only

Question 3

How is glycogen breakdown regulated?

Answer 3

Regulation occurs mainly through allosteric control and hormonal regulation but can also occur via feedback inhibition or Phosphorylation/Dephosphorylation

Question 4

Which hormones regulate glycogen breakdown?

Answer 4

Glucagon (Liver) and Epinephrine (Muscle and Liver) both activate glycogen breakdown

Question 5

What are the Allosteric Regulators of Glycogenolysis?

Answer 5

Activation: Low energy (AMP)
Inhibition: Glucose and glucose-6-phosphate inhibit glycogen phosphorylase (Liver)