- Phosphofructokinase 2
Phosphofructokinase-2 (PFK2) is one activity of a bifunctional
enzyme (EC number|2.7.1.105), the other of which isfructose 2,6-bisphosphatase (FBPase2). Whenserine 32 is phosphorylated, the negative charge causes the conformation of the enzyme to favor the FBPase2 activity. When not phosphorylated, PFK2's activity is favored.Function
This 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 orepinephrine - PFK2 and FBPase2 form, or hydrolyze, respectively, the compoundβ-D-fructose 2,6-bisphosphate (F-2,6-BP), a regulatory molecule controlling the activity of the enzymephosphofructokinase-1 or PFK1 (inmammal s). PFK1, in turn, is a key regulatory enzyme in the central metabolic pathway - glycolysis. When PFK2 activity is favored, ADP is formed fromATP in the phosphorylation offructose-6-phosphate to F-2,6-BP. The ADP acts as apositive effector ligand PFK1, which converts fructose-6-phosphate (F-6-P) into F-1,6-BP. Thus, PFK2 increases the rate at which the principal food molecule glucose is broken down. At the same time, F-2,6-BP 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 (afutile cycle ).External links
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*, Gene|PFKFB2
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