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
Use of Okadaic Acid to Identify Relevant Phosphoepitopes in Pathology: A Focus on Neurodegeneration
TL;DR: The use of okadaic acid is reviewed to identify specific phosphoepitopes mainly in proteins relevant for neurodegeneration and the ability of OA to block the high turnover phosphorylation, thus allowing the detection of modified residues that could be otherwise difficult to identify.
Journal ArticleDOI
Protein phosphatases 1 and 2A and their naturally occurring inhibitors: current topics in smooth muscle physiology and chemical biology.
TL;DR: Protein phosphatases 1 and 2A and their naturally occurring inhibitors: current topics in smooth muscle physiology and chemical biology was originally published electronically on the publisher's internet portal (currently SpringerLink) on 5th July 2017 without open access.
Journal ArticleDOI
Reduction of protein phosphatase 2A Cα enhances bone formation and osteoblast differentiation through the expression of bone-specific transcription factor Osterix
TL;DR: The data indicate that PP2A Cα plays an important role in the regulation of bone formation and osteoblast differentiation through the bone-related genes.
Journal ArticleDOI
Ca2+/calmodulin-activated protein phosphatase: (PP2B) of Saccharomyces cerevisiae PP2B activity is not essential for growth
TL;DR: The results indicated that CMP1 and CMP2 are the only genes that encode the PP2B catalytic polypeptide in S. cerevisiae, andPP2B activity is not essential for the growth of the yeast under normal conditions.
Journal ArticleDOI
Early Genotoxic and Cytotoxic Effects of the Toxic Dinoflagellate Prorocentrum lima in the Mussel Mytilus galloprovincialis
María Verónica Prego-Faraldo,Vanessa Valdiglesias,Blanca Laffon,Josefina Méndez,José M. Eirín-López +4 more
TL;DR: Examination of the in vivo effects of the exposure to the DSP-toxin-producing dinoflagellate Prorocentrum lima during the simulation of an early HAB episode in the mussel Mytilus galloprovincialis revealed that in vivo exposure to this toxic microalgae induced early genotoxicity in hemocytes, as a consequence of oxidative DNA damage.
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.