Biochemistry, Glycogenolysis

Glycogen, also known as animal starch, is a branched polysaccharide that serves as an energy reserve in the liver and muscle. It is readily available as an immediate source of energy. The formation of glycogen from glucose is called glycogenesis, and the breakdown of glycogen to form glucose is called glycogen metabolism or glycogenolysis. Increased cyclic adenosine monophosphate (cAMP) produces the breakdown of glycogen (glycogenolysis). Various hormones such as insulin, glucagon, cortisol, and others regulate the relationship between glycogenesis and gluconeogenesis. Glycogenolysis is initiated by the action of a specific enzyme called phosphorylase, which yields glucose-1-phosphate. Glucose-1-phosphate is an important compound at the intersection of several metabolic pathways, such as glycolysis, glycogenesis, glycogenolysis, and gluconeogenesis. Interestingly, when glycogenesis occurs, glycogenolysis is inhibited, and vice versa. Impaired glycogen metabolism is associated with various inherited metabolic disorders collectively known as glycogen storage diseases.