title: Inorganic phosphate amplifies the effects of AMP and fructose-2,6-bisphosphate on yeast phosphofructokinase.
abstract: Inorganic phosphate is an important regulator of yeast phosphofructokinase activity. In the absence of AMP and fructose-2,6-bisphosphate the dependence of enzyme activity on the concentration of inorganic phosphate is sigmoidal. AMP and fructose-2,6-bisphosphate increase the affinity of phosphofructokinase to inorganic phosphate. At low fructose-6-phosphate concentrations inorganic phosphate amplifies the activating effect of AMP and fructose-2,6-bisphosphate. Yeast phosphofructokinase is more sensitive to ATP inhibition in the absence of inorganic phosphate than in its presence. While in the absence of inorganic phosphate a definite ATP inhibition prevails even at high levels of AMP or fructose-2,6-bisphosphate, the ATP inhibition can be relieved by the cooperation of inorganic phosphate and fructose-2,6-bisphosphate. These effects of inorganic phosphate provide an explanation for the stimulation of glycolysis under anaerobic conditions by inorganic phosphate at unchanged concentrations of AMP and fructose-2,6-bisphosphate (Lagunas and Gancedo, Eur. J. Biochem. 137, 479-483 (1983)).
mesh_terms: D000249:Adenosine Monophosphate / Q000494:pharmacology*; D004789:Enzyme Activation; D005635:Fructosediphosphates / Q000494:pharmacology*; D006598:Hexosediphosphates / Q000494:pharmacology*; D007700:Kinetics; D010710:Phosphates / Q000494:pharmacology*; D010732:Phosphofructokinase-1 / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*
chemical_list: D005635:Fructosediphosphates; D006598:Hexosediphosphates; D010710:Phosphates; D000249:Adenosine Monophosphate; D010732:Phosphofructokinase-1; C029063:fructose-1,6-diphosphate