Fructose-1,6-bisphosphatase control

Aldolase and Fructose Bisphosphatase Key Enzymes in the Control of Gluconeogenesis and Glycolysis B. L. Horecker, John S. MacGregor,... 

The most potent positive allosteric effector of phospho-ffuctokinase-1 and inhibitor of fructose-1,6-bisphos-phatase in liver is fructose 2,6-bisphosphate. It relieves inhibition of phosphofructokinase-1 by ATP and increases affinity for fructose 6-phosphate. It inhibits fructose-1,6-bisphosphatase by increasing the for fructose 1,6-bisphosphate. Its concentration is under both substrate (allosteric) and hormonal control (covalent modification) (Figure 19-3). 

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] ...

For values during an intravenous fructose tolerance test in controls and individuals with deficiencies of fructokinase, fructaldolase, and fructose- 1,6-bisphosphatase, see Steinmann et al. [36]. 

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.

Figure 30.6. Regulation of Gluconeogenesis. Fructose 1,6-bisphosphatase is the principal enzyme controlling the rate of gluconeogenesis.

Fructose 1,6 bisphosphatase - The primary regulatory enzyme for gluconeogenesis. Inactivated potently by F2,6BP (See Figure 16.17) and AMP. Synthesis of the enzyme is sensitive to hormonal control. 

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