In vivo regulation of muscle glycogen synthase and the control of glycogen synthesis.

摘要: The activity of glycogen synthase (GSase; EC 2.4.1.11) is regulated by covalent phosphorylation. Because this regulation, GSase has generally been considered to control the rate synthesis. This hypothesis examined in light recent vivo NMR experiments on rat and human muscle found be quantitatively inconsistent with data under conditions Our first showed that synthesis was slower non-insulin-dependent diabetics compared normals their defect glucose transporter/hexokinase (GT/HK) part pathway. From these other results a quantitative model proposed which GT/HK steps normal humans muscle. flux through match proximal "feed forward" 6-phosphate, positive allosteric effector all forms GSase. Recent specifically designed test are analyzed metabolic theory it shown step controls Preliminary evidence favors transporter step. Several conclusions significant: (i) transport/hexokinase flux; (ii) role phosphorylation adapt enzyme metabolite levels not (iii) needed for inferring testing present depended upon advances methods accurately measured concentration 6-phosphate