A metal-dependent form of protein phosphatase 2A.
Highly purified bovine heart protein phosphatase 2A catalytic subunit lost virtually all of its activity during storage at -70 degrees. When the enzyme was preincubated with Co2+, over 35% of the original activity was restored. Freshly prepared protein phosphatase 2A purified from bovine heart was stimulated at least 3 to 4-fold by pretreatment with Co2+ or Mn2+. Activation by Co2+ appeared to be irreversible whereas activation by Mn2+ was partially reversed after the cation was chelated with excess EDTA/EGTA. The sensitivity of Co2(+)-stimulated protein phosphatase 2A to okadaic acid or inhibitor-2 was similar to that of spontaneously active protein phosphatase 2A. The enzyme was converted to a latent form by treatment with phosphate or pyrophosphate. The latent form was completely reactivated by preincubation with Co2+. These results demonstrate that protein phosphatase 2A, like phosphatase 1, can exist in a metal ion-dependent form and may represent a new mechanism for the regulation of protein phosphatase 2A activity.
Cai
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Department of Pharmacology Medical College of Ohio, Toledo 43699.
Chu
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Wilson
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Schlender
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KK
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D002413:Cations, Divalent / Q000494:pharmacology; D002417:Cattle; D003035:Cobalt / Q000494:pharmacology*; D004492:Edetic Acid / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004789:Enzyme Activation; D004795:Enzyme Stability; D004988:Ethers, Cyclic / Q000494:pharmacology; D005615:Freezing; D007527:Isoenzymes / Q000378:metabolism*; D007700:Kinetics; D008345:Manganese / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009206:Myocardium / Q000201:enzymology*; D019319:Okadaic Acid; D009842:Oligopeptides / Q000276:immunology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D054645:Protein Phosphatase 1; D054648:Protein Phosphatase 2
D000906:Antibodies; D002413:Cations, Divalent; D004988:Ethers, Cyclic; D007527:Isoenzymes; D009842:Oligopeptides; D019319:Okadaic Acid; D003035:Cobalt; D008345:Manganese; D004533:Egtazic Acid; D004492:Edetic Acid; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D054648:Protein Phosphatase 2