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Vanadate

About: Vanadate is a research topic. Over the lifetime, 4497 publications have been published within this topic receiving 120109 citations. The topic is also known as: vanadate.


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Journal ArticleDOI
TL;DR: K influx into resealed human red cell ghosts increases when the ghosts are swollen or when NO3 is replaced by Cl, and the volume-sensitive influx is inhibited by Mg2+ and by high concentrations of vanadate, but is stimulated by low concentrations ofVanadate.
Abstract: K influx into resealed human red cell ghosts increases when the ghosts are swollen. The influx demonstrates properties similar to volume-sensitive K fluxes present in other cells. The influx is, for the most part, insensitive to the nature of the major intracellular cation and therefore is not a K-K exchange. The influx is much greater when the major anion is Cl than when the major anion is NO3; Cl stimulates the flux and, at constant Cl, NO3 inhibits it. Increase in the influx rate is rapid when shrunken ghosts are swollen or when NO3 is replaced by Cl. The volume-sensitive K influx requires intracellular MgATP at low concentrations, and ATP cannot be replaced by nonhydrolyzable ATP analogues. The volume-sensitive influx is inhibited by Mg2+ and by high concentrations of vanadate, but is stimulated by low concentrations of vanadate. It is not modified by cAMP, the removal of Ca2+ by EGTA, substances that activate protein kinase C, or by inhibition of phosphatidylinositol kinase. The influx is inhibited by neomycin and by trifluoperazine.

41 citations

Journal ArticleDOI
TL;DR: This phosphorylated intermediate from maize-root microsomes exhibits molecular properties characteristic of transport ATPases such as the yeast plasma membrane H+-translocating ATPase, which indicates existence of a transport ATPase in plant plasma membranes.
Abstract: A maize-root microsomal fraction was enriched in ATPase by treatment with Triton X-100. This activity, which reached 1.2–2.0/μmol Pi× min−1× gm protein−1, was specific for ATP, very slightly stimulated by K+, inhibited by orthovanadate and diethylstibestrol, resistant to oligomycin and azide, and had a Km of 1.2 mM MgATP. Incubation of th emicrosomal fraction with [y32-P]ATP followed by electrophoresis in acid conditions revealed the presence of several phosphoproteins. The phosphorylation of a 110000-M4 polypeptide reached the steady-state level in less than 5 s and rapidly turned over the phosphate group. The phosphorylation level was an hyperbolic function of the [ATP] with a Km of 0.6 mM, suggesting that the rat e of Pi production was proportional to the phosphoprotein concentration. The extent of phosphoprotein was decreased by vanadate and diethylstilbestrol. The phosphorylation level was 30% decreased by 50 mM K+ or Na+ while the ATPase activity was slightly stimulated (12% and 5%. respectively). The polypeptide could not bephosphorylated in reverse by Pi. This phosphorylated intermediate from maize-root microsomes exhibits molecular properties characteristic of transport ATPases such as the yeast plasma membrance H+ -translocating ATPase. This similarity indicates existence of a transport ATPase in plant plasma membranes. Three other plant microsomal polypeptides (Mr= 52000, 17000 and 16000) and a low molecular weight component (Mr < 1000) were phosphorylated much more slowly, were not undergoing a rapid turnover and were not hydrolysed by hydroxylamine. These phosphoproteins and the Mr < 1000 phosphorylated component were inhibited by vanadate and diethylstilbestrol. These properties are similar to those of the protein kinase activity recently described in yeast plasma membranes.

41 citations

Journal ArticleDOI
TL;DR: The results suggest the existence of a chemical-hormesis phenomenon that might be subjected to sexual-genre variability and the possible causes for this double inhibition are briefly discussed.

40 citations

Journal ArticleDOI
TL;DR: It is suggested that the two phosphoenzyme species formed either from ATP or Pi, especially in their reactivity to N-methyl hydroxylamine, are two subconformations of the E2P phosphoform.
Abstract: The properties of Na,K-ATPase phosphoenzymes formed either from ATP in the presence of Mg2+ and Na+ or from Pi in the absence of alkali cations were investigated by biochemical methods and spectrofluorometry employing the styryl dye RH421. We characterized the phosphoenzyme species by their reaction to N-methyl hydroxylamine, which attacks specifically the protein-phosphate bond. We studied reactions of the phospho- and dephospho-enzymes with vanadate, which is a transition-state analogue of phosphate in this enzyme. On the basis of substantial differences in the properties of the phosphoenzyme species formed either from ATP or Pi, especially in their reactivity to N-methyl hydroxylamine, it is suggested that the two phosphoenzyme species are two subconformations of the E2P phosphoform. Analysis of the RH421 fluorescence responses under a variety of experimental conditions and comparing different enzyme sources suggested that the increase of RH421 fluorescence induced by inorganic phosphate in the absence of alkali cations is associated with the formation of the covalent acyl-phosphate bond.

40 citations

Journal ArticleDOI
TL;DR: Investigations revealed that vanadate suppressed upstream of apoptotic events, such as the loss of mitochondrial membrane potential, the conformational change of Bax, and p53 transactivation, although the accumulation, totalosphorylation, and phosphorylation of six individual sites of p53 were not affected.
Abstract: We previously reported that p42/SETβ is a substrate for caspase-7 in irradiated MOLT-4 cells, and that treating the cells with sodium orthovanadate (vanadate) inhibits p42/SETβ's caspase-mediated cleavage. Here, we initially found that the inhibitory effect of vanadate was due to the suppression of caspase activation but not of caspase activity. Further investigations revealed that vanadate suppressed upstream of apoptotic events, such as the loss of mitochondrial membrane potential, the conformational change of Bax, and p53 transactivation, although the accumulation, total phosphorylation, and phosphorylation of six individual sites of p53 were not affected. Importantly, vanadate suppressed p53-dependent apoptosis, but not p53-independent apoptosis. Finally, gel-shift and chromatin immunoprecipitation assays conclusively demonstrated that vanadate inhibits the DNA-binding activity of p53. Vanadate is conventionally used as an inhibitor of protein tyrosine phosphatases (PTPs); however, we recommend that the influence of vanadate not only on PTPs but also on p53 be considered before using it.

40 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023109
2022211
202178
202075
201996
201899