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Carbohydrate Metabolism Regulation Problem Set

Question 3: PFK-1 Regulation in Liver

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-bisphosphate
Activation of PFK-1 in liver is indirect, and occurs as follows: dephosphorylation of the bifunctional PFK-2/Fructose-bisphosphatase enzyme places this enzyme in the PFK-2 mode, producing fructose-2,6-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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March 16, 2001
Revised: August, 2004
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