Answer:
b. Phosphofructokinase; Fructose-1,6-bisphosphatase
Explanation:
Glucagon is a hormone which functions to initiate gluconeogenesis whwreas insulin functions to initiate glycolysis.
Fructose-2,6-bisphosphate (F26BP) is an allosteric regulator of the <em>glycolytic and gluconeogenic enzymes phosphofructokinase-1 (PFK-1) and fructose-1,6-bisphosphatase (FBPase-1).</em>
It stimulates glycolysis and inhibits gluconeogenesis by binding to its allosteric site on phosphofructokinase-1 reducing its affinity for the allosteric inhibitors ATP and citrate .
It is formed by phosphorylation of fructose-6-phosphate catalyzed by <em>phosphofructokinase-2</em> and is broken down by <em>fructose-2,6-bisphosphatase </em>which are two separate enzymatic activities of a single, bifunctional protein (PFK-2/FBPase-2).
Phosphorylation of PFK-2/FBPase-2 due to glucagon release enhances its FBPase-2 activity thereby stimulating gluconeogenesis and inhibiting glycolysis.
Dephosphsorylation of PFK-2/FBPase-2 due to insulin release enhances its PFK-2 activity, thereby stimulating glycolysis and inhibiting gluconeogenesis.