Which allosteric molecule is the most potent physiological activator of phosphofructokinase-1 (PFK-1) and inhibitor of fructose-1,6-bisphosphatase-1 (FBPase-1) in the liver?
Answer and explanation
Correct answer: B. Fructose-2,6-bisphosphate (F-2,6-BP)
Fructose-2,6-bisphosphate (F-2,6-BP) is a key reciprocal regulator synthesized by PFK-2/FBPase-2. High insulin levels stimulate PFK-2 activity, elevating F-2,6-BP. This allosterically activates PFK-1 (accelerating glycolysis) and inhibits FBPase-1 (shutting down gluconeogenesis), preventing futile cycling between the two opposing pathways.
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