title: The ATP, Mg-dependent phosphatase: role of Mg ions in the expression of the phosphorylase phosphatase activity.
abstract: The activation of the ATP, Mg-dependent phosphatase [FCM] by kinase FA has been shown to involve the phosphorylation or thiophosphorylation of the modulator subunit [M] and the consequent isomerization of the catalytic subunit [FC] into the active conformation. The inactive catalytic subunit [free FC] exhibits substantial activity in the presence of non-physiological concentrations of Mn ions whereas the Mn2+-activation of the intact FCM-enzyme requires the proteolytic destruction of the modulator subunit. The present study points to the importance of Mg2+ in the activation of the phosphatase. The inactive catalytic unit can be activated by millimolar concentrations of Mg2+ and the thiophosphorylated FCM-enzyme only expresses its phosphorylase phosphatase activity after a subsequent trypsin treatment in the presence of Mg ions.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D006358:Hot Temperature; D008274:Magnesium / Q000378:metabolism*; D008345:Manganese / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010765:Phosphorylase Phosphatase / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism
chemical_list: D008345:Manganese; D000255:Adenosine Triphosphate; D011494:Protein Kinases; D010749:Phosphoprotein Phosphatases; D010765:Phosphorylase Phosphatase; D010744:Phosphoric Monoester Hydrolases; D008274:Magnesium