Glycogen synthase 2

Transfers the glycosyl residue from UDP-Glc to the non-reducing end of alpha-1,4-glucan. Although the catalytic mechanisms used by glycogen synthase are not well known, structural similarities to glycogen phosphorylase at the catalytic and substrate binding site suggest that the mechanism for synthesis is similar in glycogen synthase and glycogen phosphorylase. Glycogen synthase catalyzes the conversion of the glucosyl (Glc) moiety of uridine diphosphate glucose (UDP-Glc) into glucose to be incorporated into glycogen via an α(1→4) glycosidic bond. However, since glycogen synthase requires an oligosaccharide primer as a glucose acceptor, it relies on glycogenin to initiate de novo glycogen synthesis. In a recent study of transgenic mice, an overexpression of glycogen synthase and an overexpression of phosphatase[9] both resulted in excess glycogen storage levels. This suggests that glycogen synthase plays an important biological role in regulating glycogen/glucose levels and is activated by dephosphorylation.