Fructose-bisphosphatase

CHYMOTRYPSIN FRUCTOSE-2,6-BISPHOSPHATASE ILLUSTRATE COVALENT CATALYSIS... 

Fructose-2,6-bisphosphatase, a regulatory enzyme of gluconeogenesis (Chapter 19), catalyzes the hydrolytic release of the phosphate on carbon 2 of fructose 2,6-bisphosphate. Figure 7-8 illustrates the roles of seven active site residues. Catalysis involves a catalytic triad of one Glu and two His residues and a covalent phos-phohistidyl intermediate. 

Figure 19-3. Control of glycolysis and gluconeoge-nesis in the liver by fructose 2,6-bisphosphate and the bifunctional enzyme PFK-2/F-2,6-Pase (6-phospho-fructo-2-kinase/fructose-2,6-bisphosphatase). (PFK-1, phosphofructokinase-1 [6-phosphofructo-1 -kinase] ...

There s also a fructose 2,6-bisphosphatase that hydrolyzes fructose 2,6-bisphosphate see if you can figure out what happens to the phosphatase activity in liver and muscle when the enzyme is phosphorylated. As a check to your answer, you might recall the PFK-2 and fructose 2,6-bisphosphatase are one and the same protein. Phosphorylation-dephosphorylation actually shifts the activity of this single protein between the kinase and the phosphatase. So the answer you get should be opposite to the one we got earlier. 

SORBITOL DEHYDROGENASE FRUCTOSE-1,6-BISPHOSPHATASE FRUCTOSE-2,6-BISPHOSPHATASE D-Fructose 2,6-bisphosphate, 6-PHOSPHOFRUCTO-2-KINASE Fructose-1,6-bisphosphate aldolase, ALDOLASE... 

Phosphofructokinase-2/fructose 2,6-bisphosphatase LQRRRGSSIPQ Glycolysis/gluconeogenesis... 

Figure 11-2 Roles of phosphofructose kinase and fructose 1,6-bisphosphatase in the control of the breakdown and storage (—+) of glycogen in muscle. The uptake of glucose from blood and its release from tissues is also illustrated. The allosteric effector fructose 2,6-bisphosphate (Fru-2,6-P2) regulates both phosphofructokinase and fructose 2,6-bisphosphatase. These enzymes are also regulated by AMP if it accumulates. The activity of phosphofructokinase-2 (which synthesizes Fru-2,6-P2) is controlled by a cyclic AMP-dependent kinase and by dephosphorylation by a phosphatase.

Fructose bisphosphate aldolases 699 Fructose 6-phosphate 535, 693s Fructose 6-phosphate kinase 656 Fructose-1,6-bisphosphatase 645 Fructose-2,6-bisphosphatase 646 Fruit fly. See Drosophilia melanogaster Fucose (Fuc) 165s L-Fucose isomerase 693 Fucosyltransferase 184 Fucoxanthin 22... 

The effects of ATP, AMP, and fructose 2,6-bisphos-phate on phosphofructokinase have been discussed in Chapter 11, Section C. Fructose 2,6-P2 is a potent allosteric activator of phosphofructokinase and a strong competitive inhibitor of fructose 1,6-bisphosphatase (Fig. 11-2). It is formed from fructose 6-P and ATP by the 90-kDa bifunctional phosphofructo-2-kinase/ fructose 2,6-bisphosphatase. Thus, the same protein forms and destroys this allosteric effector. Since the bifunctional enzyme is present in very small amounts, the rate of ATP destruction from the substrate cycling is small. 

Shin DJ and McGrane MM (1997) Vitamin A regulates genes involved in hepatic gluconeogenesis in mice phosphoenolpyruvate carboxykinase, fructose-l,6-bis-phosphatase and 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase./owmaZ of Nutrition 127, 1274-8. 

The crystal structure of the entire 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase, a key bifunctional regulator of both glycolysis and gluconeogenesis, has been solved at 2.0 A resolution. The entire enzyme is a homodimer of 55kDa subunits arranged in a head-to-head fashion, with each monomer consisting of an independent kinase and phosphatase domain. The location of y-5 -ATP and inorganic phosphate in the kinase and phosphatase domains,... 

Kitamura, K., Kangawa, K., Matsuo, H., Uyeda, K. (1988). Phosphorylation of myocardial fructose-6-phosphate,2-kinase fructose-2,6-bisphosphatase by cAMP-dependent protein kinase and protein kinase C. J. Biol. Chem. 263, 16796-16801. 

Pilkis, S. J., T. H. Claus, 1. J. Kurland, and A. J. Lange. 1995. 6-Phosphofructo-2-kinase/fructose-2,6-bisphosphatase a metabolic signaling enzyme. Arm. Rev. Biochem. 64 799-835. 

Phosphofructo-2-kinase-Fructose-2,6-bisphosphatase (PFK2-FBPase2)... 

When phosphorylated, PFK2, effectively is a fructose-2,6-bisphosphatase. Thus, it will carry out the reaction offructose-2,6-bisphosphate fructose-6-phosphate + inorganic phosphate. This will decrease the level of fructose-2,6-bisphosphate, removing the activation of PFK and the inhibition of FBPase, and al-... 

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