Insulin: Decreases glycogen uptake by cells Increases in concentration in the blood after a meal Promotes water reabsorption Is released in response to the onset of exercise

In the liver, insulin affects glycogen metabolism by stimulation of glycogen synthesis. Protein phosphatase I (PPI) is the key molecule in the regulation of glycogen metabolism. Via dephosphorylation, PPI slows the rate of glycogenolysis by inactivating phosphorylase kinase and phosphorylase A.