Regulation of Carbohydrate Metabolism Problem Set

Question 3: PFK-1 Regulation in Liver

Correct!

Given that the phosphofructokinase-1 (PFK-1) enzyme is regulated by insulin, but not via (de)phosphorylation, how is this regulation accomplished?

A.	Via increased transcription of the gene encoding this enzyme
B.	By recruitment of pre-existing enzyme from the Golgi
C.	Via allosteric regulation by fructose-2,6-bisphosphatase Activation of PFK-1 in liver is indirect, and occurs as follows: dephosphorylation of the bifunctional PFK-2/Fructose-bis phosphatase enzyme places this enzyme in the PFK-2 mode, producing fructose-2,3-bisP, which then allosterically activates PFK-1 (the tutorial for this question provides a diagram of this). A bit complicated, but when placed in the context of insulinšs role to promote glucose utilization/storage, it fits nicely into the big picture.
D.	Activation by association with IRS-1
E.	An inhibitory subunit of the enzyme dissociates after binding cAMP