OBB Practice Questions - Olimpíada Brasileira De Biologia Exam

High concentrations of ATP and citrate allosterically activate PFK-1 by stabilizing the high-affinity R-state conformation, whereas elevated AMP and glucagon strongly inhibit the enzyme to stimulate hepatic glycolysis during nutrient deprivation Fructose 2,6-bisphosphate acts as a potent competitive inhibitor of PFK-1 by occupying the catalytic fructose 6-phosphate binding pocket, while high cellular AMP levels promote its ubiquitination and rapid degradation by the 26S proteasome Glucagon stimulates PFK-1 by promoting the kinase activity of the bifunctional enzyme PFK-2/FBPase-2, thereby elevating intracellular levels of fructose 2,6-bisphosphate to accelerate glycolytic carbon disposal during fasting states High physiological ATP and cytosolic citrate allosterically inhibit PFK-1, whereas elevated AMP and fructose 2,6-bisphosphate relieve ATP inhibition to stimulate glycolysis