Glycogenesis is the process of glycogen synthesis, in which glucose molecules are added to chains of glycogen for storage. This process occurs in the liver and is activated during rest periods following the Cori cycle, as well as by insulin in response to high glucose levels in the body. The process of glycogenesis involves several steps, including:

• Glycogenin: The enzyme glycogenin is needed to create initial short glycogen chains, which are then lengthened and branched by the other enzymes of glycogenesis. Glycogenin has a tyrosine residue on each subunit that serves as the anchor for the reducing end of glycogen. Initially, about seven UDP-glucose molecules are added to each tyrosine residue by glycogenin, forming α(1→4) bonds.

• Glycogen synthase: Once a chain of seven glucose monomers is formed, glycogen synthase binds to the growing glycogen chain and adds UDP-glucose to the 4-hydroxyl group of the glucosyl residue on the non-reducing end of the glycogen chain, forming more α(1→4) bonds in the process.

• Glycogen branching enzyme: Branches are made by glycogen branching enzyme, which transfers the end of the chain onto an earlier part via α-1:6 glycosidic bond, forming branches, which further grow by addition of more α-1:4 glycosidic units.

Glycogenesis is stimulated by the hormone insulin, which facilitates the uptake of glucose into muscle cells and stimulates glycogenesis in liver cells while inhibiting glycogenolysis, the breakdown of glycogen into glucose. Glycogenesis responds to hormonal control, and one of the main forms of control is the varied phosphorylation of glycogen synthase and glycogen phosphorylase.