Van Schaftingen E
Laboratoire de Chimie Physiologique, Université Catholique de Louvain, Brussels, Belgium.
Diabetologia. 1994 Sep;37 Suppl 2:S43-7. doi: 10.1007/BF00400825.
The activity of liver glucokinase is controlled in the short term by the concentration of its substrate glucose and by a regulatory protein, which acts as a competitive inhibitor with respect to glucose. In mammalian species, the effect of this protein is modulated by fructose 6-phosphate, which reinforces the inhibition, and by fructose 1-phosphate which antagonizes it. In the rat, the regulatory protein is found in the two tissues that express glucokinase, i.e., the liver and the pancreatic islets. Of particular interest is the fact that the regulatory protein is absent from the liver in those species that have no hepatic glucokinase. These results indicate that the two proteins form a functional unit. The regulatory protein appears in rat liver before birth, whereas glucokinase is only synthesized after 15 days of extrauterine life. The concentration of regulatory protein in the liver of the adult rat decreases by about 50% during starvation and in diabetes mellitus. Under these conditions, the difference between the concentrations of regulatory protein and glucokinase remains constant at about 0.4-0.5 nmol/g.
肝脏葡萄糖激酶的活性在短期内受其底物葡萄糖浓度以及一种调节蛋白的控制，该调节蛋白对葡萄糖起竞争性抑制作用。在哺乳动物中，这种蛋白质的作用受到6-磷酸果糖的调节，6-磷酸果糖会增强抑制作用，而1-磷酸果糖则起拮抗作用。在大鼠中，调节蛋白存在于表达葡萄糖激酶的两个组织中，即肝脏和胰岛。特别值得注意的是，在没有肝葡萄糖激酶的物种中，肝脏中不存在调节蛋白。这些结果表明这两种蛋白质形成了一个功能单元。调节蛋白在大鼠肝脏出生前就已出现，而葡萄糖激酶仅在出生后15天开始合成。成年大鼠肝脏中调节蛋白的浓度在饥饿和糖尿病期间会降低约50%。在这些情况下，调节蛋白和葡萄糖激酶浓度之间的差异保持在约0.4 - 0.5 nmol/g的恒定水平。
