A 15-year-old type I diabetic faints after injecting himself with insulin. He is administered Glucagon and rapidly recovers consciousness. Glucagon induces activity of:

Glucagon (catabolic hormone) activates the Rate limiting enzyme of glycogenolysis (catabolic pathway) i.e. Glycogen phosphorylase. ADDITIONAL EDGE: Fig.: In fasting state, Glucagon hormone is released. Regulation of glycogen metabolism at the level of glycogen phosphorylase: cAMP activates phosphorylase kinase (by a cAMP-dependent protein kinase), which in turn activates glycogen phosphorylase. Calcium activates the calmodulin component of phosphorylase kinase directly, which in turn activates glycogen phosphorylase. 5' AMP acts allosterically to activate glycogen phosphorylase. Protein phosphatase-1 inactivates glycogen phosphorylase.