Roach P J, Larner J
J Biol Chem. 1976 Apr 10;251(7):1920-5.
The effects of several inhibitors (ATP, ADP, AMP, UDP, and P1) and activators (Mg2+, glucose-6-P) of rabbit muscle glycogen synthase (UDP-glucose:glycogen 4-alpha-glucosyltransferase, EC 2.4.1.11) were studied in relation to the phosphorylation state of the purified enzyme. All the modifiers had increasing effects with enzyme of increasing alkali-labile phosphate content. In experiments where combinations of effectors were present, it was apparent that (a) concentrations of modifiers in the physiological range could be significant in determining enzymic activity and (b) the sensitivity of the reaction rate to changes in phosphorylation state was critically dependent on the concentration of the small molecules. Changes in the phosphorylation of the enzyme corresponding to changes in the %I activity reported in the literature for studies in vivo were capable of producing large alterations in glycogen synthase activity. Because the magnitudes of such changes were dependent on the effector concentrations, there may be an integration of local cellular control, through small molecule effects, with hormonal control, through the phosphorylation state of glycogen synthase.
研究了几种抑制剂（ATP、ADP、AMP、UDP和P1）和激活剂（Mg2+、6-磷酸葡萄糖）对兔肌肉糖原合酶（UDP-葡萄糖：糖原4-α-葡糖基转移酶，EC 2.4.1.11）的作用，并与纯化酶的磷酸化状态相关联。所有修饰剂对碱不稳定磷酸盐含量增加的酶都有增强作用。在存在效应物组合的实验中，很明显：（a）生理范围内修饰剂的浓度在决定酶活性方面可能具有重要意义；（b）反应速率对磷酸化状态变化的敏感性严重依赖于小分子的浓度。与文献中报道的体内研究中%I活性变化相对应的酶磷酸化变化能够使糖原合酶活性产生很大改变。由于这种变化的幅度取决于效应物浓度，通过小分子效应的局部细胞控制可能与通过糖原合酶磷酸化状态的激素控制存在整合。
