Glucokinase phosphorylates glucose only when it is abyndant because it has a much higher KM for glucose than does hexokinase. The role of glucokinase is to provide glucose-6-P for the synthesis of glycogen, a storage fom of glucose. The high KM of glucokinase in the liver gives barin and muscle first call on glucose when its supply is limited.

Fructose-6-P inhibites it by negative feedback.