A patient comes into your clinic suffering from anorexia nervosa. Her mother brought her in concerned as the patient has not eaten in over 3 days. She has the classic presentation including low body weight, decreased muscle mass, decreased glycogen, and decreased fat stores, and she is anemic (low red blood cell count). What would be the expected phosphorylation state and activity of the patient's liver glycogen phosphorylase?

• A. Phosphorylated & active.
• B. Dephosphorylated & active.
• C. Phosphorylated & inactive.
• D. Dephosphorylated & inactive.

Answer: (A)

Verified step by step guidance

1. Understand the role of glycogen phosphorylase: Glycogen phosphorylase is an enzyme that breaks down glycogen into glucose-1-phosphate, which can then be converted into glucose-6-phosphate for energy production. It is regulated by phosphorylation, which affects its activity.
2. Consider the metabolic state of the patient: The patient has not eaten for over 3 days, indicating a fasting state. During fasting, the body needs to mobilize stored energy sources, such as glycogen, to maintain blood glucose levels.
3. Determine the hormonal regulation during fasting: In a fasting state, glucagon levels are elevated, and insulin levels are low. Glucagon activates protein kinase A (PKA), which phosphorylates glycogen phosphorylase, thereby activating it.
4. Assess the phosphorylation state: Given the fasting state and the hormonal signals, glycogen phosphorylase in the liver is expected to be phosphorylated, which is the active form of the enzyme.
5. Conclude the expected activity: Since the enzyme is phosphorylated, it is active, allowing the liver to break down glycogen to release glucose into the bloodstream, helping to maintain energy levels during fasting.