Rapid Activation-Inactivation of Liver Uridine Diphosphate Glucose-Glycogen Transferase and Phosphorylase by Insulin and Glucagon in Vivo

Abstract

Abstract Insulin administered in vivo activates dog liver uridine diphosphate glucose-glycogen transferase within 7 to 13 min. It also inactivates phosphorylase. Glucagon reverses these changes equally rapidly. Transferase I has an apparent Km for UDP-glucose which is calculated to be 17-fold lower than that for transferase D. Interconversion of transferase D and I activities in liver is suggested to occur and to be catalyzed by an enzymic system which may be similar to that in muscle.