Question

In: Biology

Describe the role of the bifunctional enzyme in the reciprocal regulation of glycolysis and gluconeogenesis.

Describe the role of the bifunctional enzyme in the reciprocal regulation of glycolysis and gluconeogenesis.

Solutions

Expert Solution

When an enzyme perform both on and off function of a pathway it is called as bifunctional enzyme. Phosphofructokinase -2 (PFK-2)/ fructose2,6- bisphosphatase (FBPase-2) is a best example for that. This is a potent regulator of glycolysis. This indirectly regulate this pathway.

Fructose 2,6-bisphosphate (F2,6 -BP) regulates the glycolysis directly. This molecule gets activated or deactivated by phosphorylation or dephosphorylation respectively.

# When F2,6-BP is active, it stimulates glycolysis and inhibits gluconeogenesis. Here PFK-2 adds one phosphate to F6-P and convert into F2,6-BP (Active).

# When F2,6-BP is inactive, it inhibits glycolysis and stimulates gluconeogenesis. Here FBPase-2 removes a phosphate from F2,6-BP and convert it into F6-P (Inactive). This cannot induce glycolysis.

So the phosporylation and dephosphorylation of F6-P/ F2,6-BP switches the reciprocal regulation glycolysis and gluconeogenesis.


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