title: On the dephosphorylation of the ATP,Mg-dependent protein phosphatase modulator.
abstract: The dephosphorylation of the modulator subunit is an essential step in the kinase FA-mediated activation of the ATP,Mg-dependent protein phosphatase. Mg2+ is implicated in this autocatalytic dephosphorylation which is not effected by the addition of phosphoinhibitor-1. Dephosphorylation of free modulator by the catalytic subunit is also largely Mg2+-dependent but can be abolished by phosphoinhibitor-1 in concentrations comparable to the amount of modulator used as substrate (micromolar). The phosphorylase phosphatase activity of the catalytic subunit is inhibited by nanomolar concentrations of phosphoinhibitor-1 and is completely independent of divalent cations.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000494:Allosteric Regulation; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000378:metabolism; D046911:Macromolecular Substances; D008274:Magnesium / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D010765:Phosphorylase Phosphatase / Q000378:metabolism*; D011494:Protein Kinases / Q000502:physiology
chemical_list: D004791:Enzyme Inhibitors; D046911:Macromolecular Substances; D010750:Phosphoproteins; D000255:Adenosine Triphosphate; D011494:Protein Kinases; D010749:Phosphoprotein Phosphatases; D010765:Phosphorylase Phosphatase; D008274:Magnesium