A study of supramolecular organization of glycogenolytic enzymes in vertebrate muscle tissue.

Under conditions preventing the direct binding of phosphorylase kinase to glycogen, we detected the formation of the compound ternary complex of glycogen, phosphorylase and phosphorylase kinase. The complex formation occurs in two stages: (i) the formation of phosphorylase-glycogen complex controlled by ATP, (ii) the binding of phosphorylase kinase to the previously formed phosphorylase-glycogen complex exclusively in the presence of Ca2+ and Mg2+. The process is responsible for the increase of phosphorylase kinase activity in the presence of glycogen. An opinion is offered that a specific order of enzyme binding to glycogen particle as support provides for a self-assembly of the studied metabolon and plays an essential role in the regulation of glycogenolysis.