Inhibitory effect of a marine-sponge toxin, okadaic acid, on protein phosphatases. Specificity and kinetics
Corinna Bialojan,Akira Takai +1 more
Reads0
Chats0
TLDR
Kinetic studies showed that okadaic acid acts as a non-competitive or mixed inhibitor on the okadaIC acid-sensitive enzymes.Abstract:
The inhibitory effect of a marine-sponge toxin, okadaic acid, was examined on type 1, type 2A, type 2B and type 2C protein phosphatases as well as on a polycation-modulated (PCM) phosphatase. Of the protein phosphatases examined, the catalytic subunit of type 2A phosphatase from rabbit skeletal muscle was most potently inhibited. For the phosphorylated myosin light-chain (PMLC) phosphatase activity of the enzyme, the concentration of okadaic acid required to obtain 50% inhibition (ID50) was about 1 nM. The PMLC phosphatase activities of type 1 and PCM phosphatase were also strongly inhibited (ID50 0.1-0.5 microM). The PMCL phosphatase activity of type 2B phosphatase (calcineurin) was inhibited to a lesser extent (ID50 4-5 microM). Similar results were obtained for the phosphorylase a phosphatase activity of type 1 and PCM phosphatases and for the p-nitrophenyl phosphate phosphatase activity of calcineurin. The following phosphatases were not affected by up to 10 microM-okadaic acid: type 2C phosphatase, phosphotyrosyl phosphatase, inositol 1,4,5-trisphosphate phosphatase, acid phosphatases and alkaline phosphatases. Thus okadaic acid had a relatively high specificity for type 2A, type 1 and PCM phosphatases. Kinetic studies showed that okadaic acid acts as a non-competitive or mixed inhibitor on the okadaic acid-sensitive enzymes.read more
Citations
More filters
Journal ArticleDOI
Reversible phosphorylation as a controlling factor for sustaining calcium oscillations in HeLa cells: Involvement of calmodulin-dependent kinase II and a calyculin A-inhibitable phosphatase.
TL;DR: Results show that intracellular Ca2+ cannot oscillate when CaMK II is locked in either the inactive or the stimulated state, consistent with the concept that repetitive phosphorylation-dephosphorylation cycles regulating IP3R and Ca2 + pumps are a controlling factor for sustained Ca 2+ oscillations in HeLa, and possibly other, cells.
Book ChapterDOI
Function and regulation of cdc25 protein phosphatase through mitosis and meiosis
Catherine Jessus,René Ozon +1 more
TL;DR: It is highly probable that a distinct protein kinase is involved as a trigger in cdc25 activation and the implication of raf kinase as a cDC25-specific activating kinase in human cells and Xenopus oocytes is discussed.
Journal ArticleDOI
Multiple second messenger systems act sequentially to mediate rolipram-induced prolongation of prostaglandin E2-induced mechanical hyperalgesia in the rat.
TL;DR: Evaluated mechanisms mediating the prolonged hyperalgesia induced by administration of prostaglandin E2 plus rolipram, an inhibitor of type IV phosphodiesterase found WIPTIDE was found to be without effect, and H-8, a protein kinase G inhibitor, and okadaic acid, aprotein phosphatase inhibitor, each produced a significant reduction in the hyperAlgesiainduced by prostaglandsin E 2 plus ro Lipram.
Journal ArticleDOI
Mechanisms of agonist-dependent and -independent desensitization of a recombinant P2Y2 nucleotide receptor
Miguel A. Otero,Richard C. Garrad,Betty Velázquez,Melvin G. Hernández-Pérez,Jean M. Camden,Laurie Erb,Lane L. Clarke,John T. Turner,Gary A. Weisman,Fernando A. González +9 more
TL;DR: The present studies investigated the phenomenon of P2Y2 receptor desensitization in human 1321N1 astrocytoma cells expressing recombinant wild type and C-terminal truncation mutants of the P2,2 receptor, and suggest that phosphorylation of the C- terminus of theP2y2 receptor by protein kinases other than protein kinase C mediates agonist-induced receptor desENSitization.
Journal ArticleDOI
Derivation of toxicity equivalency factors for marine biotoxins associated with Bivalve Molluscs
Luis M. Botana,Philipp Hess,Rex Munday,Arnich Nathalie,Stacey L. DeGrasse,Mark Feeley,Toshiyuki Suzuki,Martin van den Berg,Vittorio Fattori,Esther Garrido Gamarro,Angelika Tritscher,Rei Nakagawa,Iddya Karunasagar +12 more
TL;DR: The proposed TEFs herein, when applied to toxin analogue concentrations determined using analytical methods, will provide a base to determine overall toxicity, thereby protecting human health, therebyprotecting human health.
References
More filters
Journal Article
Protein Measurement with the Folin Phenol Reagent
TL;DR: Procedures are described for measuring protein in solution or after precipitation with acids or other agents, and for the determination of as little as 0.2 gamma of protein.
Journal ArticleDOI
The direct linear plot. A new graphical procedure for estimating enzyme kinetic parameters
TL;DR: A new plot is described for analysing the results of kinetic experiments in which the Michaelis-Menten equation is obeyed, and provides clear and accurate information about the quality of the observations, and identifies aberrant observations.
Journal ArticleDOI
The kinetics of enzyme-catalyzed reactions with two or more substrates or products. II. Inhibition: nomenclature and theory.
TL;DR: A nomenclature is proposed to describe different types of inhibitions of enzyme-catalyzed reactions, particularly for reactions with more than one substrate and product, and the rate equations for such inhibitions are discussed.
Journal ArticleDOI
Discovery of A Ca2+-and calmodulin-dependent protein phosphatase
TL;DR: The serine residue on the a-sub unit, as well as that on the@subunit, becomes phosphorylated in vivo in response to adrenaline, suggesting that it may have a physiological function.
Journal ArticleDOI
The protein phosphatases involved in cellular regulation. 1. Classification and substrate specificities.
TL;DR: Examination of the amino acid sequences around each phosphorylation site does not support the idea that protein phosphatase specificity is determined by the primary structure in the immediate vicinity of the phosphorylated site, and demonstrates that proteinosphatase-1 and protein phosph atase 2A have very broad substrate specificities.