The antidiabetic agent sodium tungstate activates glycogen synthesis through an insulin receptor-independent pathway.

This work was supported by grants FIS 01/836 (Ministry of Health, Spain) and ERDF 1FD97–0812 (Ministry of Science and Technology, Spain)

Glucose has to be phosphorylated to activate glycogen synthase, but not to inactivate glycogen phosphorylase in hepatocytes

Abstract2-Deoxyglucose and 5-thioglucose, in the same fashion as glucose, cause the inactivation of the rat hepatocyte glycogen phosphorylase and the activation of glycogen synthase. However, 6-deoxyglucose and 1,5-anhydroglucitol inactivate phosphorylase without increasing the activation state of glycogen synthase. With 3-O-methylglucose no changes in the activity or these enzymes occurred. These results prove that while glucose is the molecule that triggers the inactivation of phosphorylase, glucose 6-phosphate is the signal for glucose synthase activation and that a metabolite control of the activation state of glycogen synthase is operative in hepatocytes