Potential mechanism(s) involved in the regulation of glycogen synthesis by insulin

Stimulation of glycogen synthesis is one of the major physiological responses modulated by insulin. Although, details of the precise mechanism by which insulin action on glycogen synthesis is mediated remains uncertain, significant advances have been made to understand several steps in this process. Most importantly, recent studies have focussed on the possible role of glycogen synthase kinase-3 (GSK-3) and glycogen bound protein phosphatase-1 (PP-1G) in the activation of glycogen synthase (GS) - a key enzyme of glycogen metabolism. Evidence is also accumulating to establish a link between insulin receptor induced signaling pathway(s) and glycogen synthesis. This article summarizes the potential contribution of various elements of insulin signaling pathway such as mitogen activated protein kinase (MAPK), protein kinase B (PKB), and phosphatidyl inositol 3-kinase (PI3-K) in the activation of GS and glycogen synthesis.