Question

How are phosphofructokinase and fructose-1,6-diphosphatase are regulated by fructose-2,6-diphosphate?

	A.	fructose-2,6-diphosphate acts as kinase, phosphorylating phosphofructokinase-1 and fructose-1,6-diphosphatase
	B.	fructose-2,6-diphosphate acts as a catalyst, speeding up the production of phosphofructokinase-1 and fructose-1,6-diphosphatase for ATP production
	C.	fructose-2,6-diphosphate facilitates the decarboxylation of phosphofructokinase-1 and fructose-1,6-diphosphatase
	D.	fructose-2,6-diphosphate acts as an allosteric effector for phosphofructokinase-1 and fructose-1,6-diphosphatase
	E.	none of the above

Answer 1

Answer - Option D(fructose-2,6-diphosphate acts as an allosteric effect or for phosphofructokinase-1 and fructose-1,6-diphosphatase)

Explanation - Since fructose 2,6-bisphosphate  is an activator of the glycolytic phosphofructokinase (PFK1)  as well as an inhibitor of fructose 1,6 bisphosphate the glucagon can thus reduce glycolytic flux and promote gluconeogenesis at this step as well as at the pyruvate kinase step .The fructose 2,6-bisphosphate function as a potent allosteric activator of PFK1, a rate-limiting enzyme of glycolysis. Therefore, inhibits glycolysis, thereby redirecting cellular glucose metabolism to the pentose phosphate pathway shunt.