CELL RESPIRATION
GLYCOLYSIS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Fructose 1, 6-bisphosphate; phosphofructokinase 1; positive
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Fructose 2, 6-bisphosphate; phosphofructokinase 2; positive
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Fructose 1, 6-bisphosphate; fructose 1, 6-bisphosphatase; negative
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Fructose 2, 6-bisphosphate; fructose 2, 6-bisphosphatase; negative
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Detailed explanation-1: -Fructose-2, 6-bisphosphate functions as a potent allosteric activator of PFK1, a rate-limiting enzyme of glycolysis. Therefore, TIGAR inhibits glycolysis, thereby redirecting cellular glucose metabolism to the pentose phosphate pathway shunt.
Detailed explanation-2: -In the classic view, F26P2 regulates glucose metabolism by allosteric effects on 6-phosphofructo-1-kinase (6PFK1, activation) and fructose-1, 6-bisphosphatase (FBPase, inhibition). When levels of F26P2 are high, glycolysis is enhanced and gluconeogenesis is inhibited.
Detailed explanation-3: -Note the dual action of fructose-2, 6-bisphosphate (F-2, 6-BP), which activates phosphofructokinase (PFK-l) and inactivates fructose-1, 6-bisphosphatase. The activity of F-2, 6-BP is under hormonal and substrate regulation (Figure 15-6).
Detailed explanation-4: -The synthesis of Fru-2, 6-P2 from Fru-6-P (fructose 6-phosphate) and MgATP is catalysed by PFK-2 (6-phosphofructo-2-kinase), whereas its hydrolysis to Fru-6-P and Pi is catalysed by FBPase-2 (fructose-2, 6-bisphosphatase) [1–7].