Insulin-dependent Synthesis of Liver Glucokinase in the Rat.

A glucokinase qualitatively and quantitatively adequate as the first and limiting step in the synthesis of glycogen from glucose has been recently identified in the liver of the normal fed rat. In contrast with hexokinase, glucokinase activity was found to disappear in fasted and alloxan-diabetic animals (1). A characteristic shared by deprivation of food and diabetes is the marked decrease of insulin secretion and a very low level of free insulin in plasma (2, 3). Insulin could control either the activity of the glucokinase or its synthesis. The results here described suggest that the synthesis of the enzyme is insulindependent. No hormonal effect on its activity has been detected.