PFK2

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Phosphofructokinase-2 (PFK2) is one activity of a bifunctional enzyme (EC 2.7.1.105), the other of which is Fructose 2,6-bisphosphatase (aka Fructose bisphosphatase-2; FBPase2). The bifunctional enzyme is present principally in cells that have responsibility for regulation of glucose concentrations in the bloodstream, for example, some liver cells.

In response to hormonal signals - for example, the release of insulin or epinephrine - PFK2 and FBPase2 form, or hydrolyze, respectively, the compound β-D-fructose 2,6-bisphosphate, a regulatory molecule controlling the activity of the enzyme Phosphofructokinase-1 or PFK1 (in mammals). PFK1, in turn, is the key regulatory enzyme in the central metabolic pathway - glycolysis. Fructose 2,6-bisphosphate has the effect of increasing the activity of PFK1, thus increasing the rate at which the principal food molecule glucose is broken down. At the same time, this regulatory molecule also inhibits the opposing enzyme (FBPase1) in the reverse pathway (gluconeogenesis) so that the synthesis of glucose is not taking place in the same cell where glucose is being broken down (a futile cycle).