Glycogen and glucose remain plentiful. In this postprandial or "fed" state, the liver takes in more glucose from the blood than it releases. After a meal has been digested and glucose levels begin to fall, insulin secretion is reduced, and glycogen synthesis stops. When it is needed for energy, glycogen is broken down and converted again to glucose. Glycogen phosphorylase is the primary enzyme of glycogen breakdown. For the next 8–12 hours, glucose derived from liver glycogen is the primary source of blood glucose used by the rest of the body for fuel. Glucagon, another hormone produced by the pancreas, in
Glycogen phosphorylase the subunit interface that is not present in the rabbit muscle glycogen phosphorylase (RMGP) normally used in studies. This site was not sensitive to the same inhibitors as those at the AMP allosteric site, and most success has been had synthesizing new inhibitors that mimic the structure of glucose, since glucose-6-phosphate is a known inhibitor of HLGP and stabilizes the less active T-state. These glucose derivatives have had some success in inhibiting HLGP, with predicted Ki values as low as 0.016 mM. Mutations in the muscle isoform of glycogen phosphorylase (PYGM) are associated with glycogen storage disease type V (GSD