Carbohydrate Metabolism Regulation Problem Set

Question 4: Insulin Regulation of Glucokinase

Glucokinase is also regulated by insulin in liver, but not via phosphorylation. How is this regulation accomplished?

A.	Via increased transcription of the gene encoding this enzyme This is a different type of regulation from the more rapid (de)phosphorylation mechanism, but is by no means unusual in metabolic systems. The actual mechanism of this insulin-initiated regulation is beyond the scope of this course. However, recall that glucokinase is the "high Km" kinase for glucose, so there is really no reason for it to even be around if glucose levels stay low most of the time.
B.	By recruitment of pre-existing enzyme from the Golgi
C.	Via allosteric regulation by fructose-2,6-bisphosphatase
D.	Activation by association with IRS-1
E.	An inhibitory subunit of the enzyme dissociates after binding cAMP