title: A Mg(2+)-dependent, Ca(2+)-inhibitable serine/threonine protein phosphatase from bovine brain.
abstract: The Mg(2+)-dependent serine/threonine protein phosphatases, also known as type 2C phosphatases (PP2C), belong to a gene family distinct from the other serine/threonine phosphatases and tyrosine phosphatases. Here we report the purification to apparent homogeneity of a novel Mg(2+)-dependent, Ca(2+)-inhibitable serine/threonine protein phosphatase from bovine brain. It is a type 2C enzyme in view of its Mg2+ requirement, resistance to okadaic acid and calyculin A, inability to use phosphorylase alpha as substrate, and a segment of amino acid sequence typical of all PP2C type phosphatases known to date. However, it differs from the other PP2C enzymes, particularly the mammalian PP2C alpha and -beta isoforms, in that its molecular weight, 76,000, is considerably larger and that it is inhibited by Ca2+, NaF, and polycations, but not by orthovanadate. The Ca2+ inhibition may not be related to its cellular regulation because of Ki values in the 20-90 microM range, but this property permits distinction of this enzyme from the other phosphatases. Although the precise physiological role of this phosphatase is not yet known, its ability to dephosphorylate a wide variety of phosphoproteins and its broad distribution, as shown by a survey of mouse tissues for its activity, suggest that it may serve an important cellular function.
authors.affiliation: Laboratory of Biochemistry, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: F
authors.initials: F
authors.lastname: Santini
authors.forename: K
authors.initials: K
authors.lastname: Qin
authors.forename: C Y
authors.initials: CY
authors.lastname: Huang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002118:Calcium / Q000494:pharmacology*; D002412:Cations / Q000494:pharmacology; D002417:Cattle; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004988:Ethers, Cyclic / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology*; D008387:Marine Toxins; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009419:Nerve Tissue Proteins / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D019319:Okadaic Acid; D010080:Oxazoles / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors; D010764:Phosphorylase Kinase / Q000378:metabolism; D010762:Phosphorylase a / Q000378:metabolism; D011487:Protein Conformation; D054648:Protein Phosphatase 2; D000071636:Protein Phosphatase 2C; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D002412:Cations; D004791:Enzyme Inhibitors; D004988:Ethers, Cyclic; D008387:Marine Toxins; D009419:Nerve Tissue Proteins; D010080:Oxazoles; D029701:Saccharomyces cerevisiae Proteins; D019319:Okadaic Acid; C059041:calyculin A; D010762:Phosphorylase a; D010764:Phosphorylase Kinase; C087358:PTC1 protein, S cerevisiae; D010749:Phosphoprotein Phosphatases; C000607466:Ppm1a protein, mouse; D054648:Protein Phosphatase 2; D000071636:Protein Phosphatase 2C; D010744:Phosphoric Monoester Hydrolases; D008274:Magnesium; D002118:Calcium