Glycolysis cholesterol synthesis, two important ways of utilizing excess glucose when its concentration is high in blood. The rate limiting enzymes catalyzing these reactions perform these functions when they have been dephosphorylated through the action of insulin on the liver cells. Between meals, during fasting, exercise or hypoglycemia, glucagon and epinephrine are released into the blood. This causes liver glycogen to be converted back to G6P, and then converted to glucose by the liver-specific enzyme glucose 6-phosphatase and released into the blood. Glucagon and epinephrine also stimulate gluconeogenesis, which coverts non-carbohydrate substrates into G6P, which joins the G6P derived from glycogen,
Glycogen storage disease type V the operation of ATPases. This is due to the lack of normal pH fall during exercise, which impairs the creatine kinase equilibrium and exaggerates the rise of ADP. Myophosphorylase is involved in the breakdown of glycogen to glucose for use in muscle. The enzyme removes 1,4 glycosyl residues from outer branches of glycogen and adds inorganic phosphate to form glucose-1-phosphate. Cells form glucose-1-phosphate instead of glucose during glycogen breakdown because the polar, phosphorylated glucose cannot leave the cell membrane and so is marked for intracellular catabolism. Myophosphorylase exists in the active form when phosphorylated. The enzyme phosphorylase kinase plays a