title: Phosphorylation of isocitrate dehydrogenase as a demonstration of enhanced sensitivity in covalent regulation.
abstract: The sensitivity to regulation of proteins undergoing covalent modification can be greatly increased when the substrates saturate the converter enzymes. This phenomenon, termed zero-order ultrasensitivity, has been found to occur in the reversible phosphorylation of isocitrate dehydrogenase. The possibility that this enhanced sensitivity is a common feature of covalent regulatory systems is discussed.
mesh_terms: D000494:Allosteric Regulation; D004789:Enzyme Activation; D007521:Isocitrate Dehydrogenase / Q000378:metabolism*; D007700:Kinetics; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism
chemical_list: D010750:Phosphoproteins; D007521:Isocitrate Dehydrogenase; D011494:Protein Kinases; D010749:Phosphoprotein Phosphatases