Biochemistry at The Biology Project

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 insulin�s 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

[Problem 3] [Tutorial] [Problem 4]

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