BIOC 3560 Lecture Notes - Lecture 11: Phosphofructokinase 2, Fructose, Gluconeogenesis
23 Apr 2019
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Document Summary
Glycolysis and gluconeogenesis are opposing cellular processes. Running both in parallel would simply waste energy. Regulation of these two processes is therefore coordinated. [fructose 2,6-bp] allosterically regulates pfk-1 and fbpase-1 in a reciprocal manner. Pfk-1 has low affinity for fructose 6-p in the absence of fructose 2,6-bp (blue line) In the presence of fructose 2,6-bp, affinity increases more than 100x (note log scale) (red line) Fructose 2,6-bp greatly decreases fructose 1,6- bisphosphatase-1 activity. Fbpase-1 has low affinity for fructose 1,6-bp in the presence of fructose 2,6-bp (red line) Fructose 2,6-bp also makes fbpase-1 more sensitive to inhibition by another allosteric regulator, amp. Increased amp levels indicate low cellular energy, therefore drives glycolysis. In the absence of fructose 2,6-bp, fbpase-1 affinity for fructose 1,6-bp increases greatly (blue line) Fructose 2,6-bp concentration is controlled by two opposing enzyme activities: phosphofructokinase-2 (pfk-2, fructose 2,6-bisphosphatase (fbpase-2) There is a single bifunctional protein which can have.
