Nielsen J N, Richter E A
Department of Human Physiology, Copenhagen Muscle Research Centre, Institute of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark.
Acta Physiol Scand. 2003 Aug;178(4):309-19. doi: 10.1046/j.1365-201X.2003.01165.x.
Glycogen synthase (GS) catalyses the incorporation of uridine diphosphate-glucose into glycogen in skeletal muscle. In concert with the glucose transport step, GS activity is thought to be rate-limiting in the disposal of glucose as muscle glycogen. Glycogen synthase is regulated by both allosteric factors (primarily glucose 6-phosphate) and covalent modification by reversible phosphorylation and dephosphorylation leading to inactivation and activation of GS, respectively. Exercise activates both stimulatory and inhibitory regulators of GS and it is thought that the resultant activity of GS during exercise depends on the relative strength of opposing signals. However, the mechanisms by which exercise regulates GS activity are not fully understood. Glycogen breakdown, the GM-protein phosphatase 1 complex and possibly cellular relocalization of GS may be considered important factors involved in the stimulation of GS activity during exercise, while adenosine monophosphate-activated protein kinase and plasma adrenaline (via protein kinase A) can be considered as essential for the exercise-induced inhibitory signals to GS.
糖原合酶（GS）催化尿苷二磷酸葡萄糖掺入骨骼肌中的糖原。与葡萄糖转运步骤协同作用，GS活性被认为是葡萄糖作为肌肉糖原处置过程中的限速因素。糖原合酶受变构因子（主要是6-磷酸葡萄糖）以及可逆磷酸化和去磷酸化的共价修饰调节，分别导致GS失活和激活。运动可激活GS的刺激和抑制调节因子，并且认为运动期间GS的最终活性取决于相反信号的相对强度。然而，运动调节GS活性的机制尚未完全了解。糖原分解、GM-蛋白磷酸酶1复合物以及GS可能的细胞重新定位可被视为运动期间刺激GS活性的重要因素，而单磷酸腺苷激活的蛋白激酶和血浆肾上腺素（通过蛋白激酶A）可被视为运动诱导的GS抑制信号所必需的因素。
