title: Resolution of bovine brain calcineurin subunits: stimulatory effect of subunit B on subunit A phosphatase activity.
abstract: Calcineurin was dissociated into subunits A and B by SDS and the dissociated subunits were separated by Sephadex G-100 column chromatography in SDS. The phosphatase activity was associated with the A subunit and was detected only in the presence of MnCl2 of the various divalent cations tested. The Mn2+-dependent phosphatase of A subunit was stimulated (4-5-fold) by calmodulin. The subunit B increased only modestly Mn2+ stimulated phosphatase activity of subunit A but markedly increased it when assay also contained calmodulin. These results support the view that subunit B plays an important role in Mn2+/calmodulin regulation of subunit A phosphatase activity. They also lend further support to our earlier postulate ([1984] FEBS Lett. 169, 251-255) that Mn2+ is a powerful regulator of calcineurin phosphatase.
mesh_terms: D000818:Animals; D001921:Brain / Q000201:enzymology*; D002147:Calmodulin / Q000494:pharmacology; D002148:Calmodulin-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D002417:Cattle; D002850:Chromatography, Gel; D003956:Dialysis; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D008345:Manganese / Q000494:pharmacology; D010446:Peptide Fragments / Q000502:physiology
chemical_list: D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D010446:Peptide Fragments; D008345:Manganese