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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: These studies demonstrate that activation of phospholipase C, if not an obligatory step in the action of all growth factors, plays a crucial role in the mitogenic signaling pathway of alpha-thrombin.

72 citations

Journal ArticleDOI
TL;DR: Genistein, a tyrosine kinase inhibitor, significantly attenuated the ability of MgATP to stimulate PLD activity and accumulation of tyrosin-phosphorylated proteins in the washed GTP[S]-treated cells, suggesting thatPLD activity in myeloid leucocytes involves co-ordinate regulation by both G-protein(s) and tyrosines phosphorylation.
Abstract: The regulation of phospholipase D (PLD)-type effector enzymes by G-proteins and protein kinases/phosphatases was characterized in the U937 human promonocytic leucocyte line. PLD activity was assayed by measuring (in the presence of 1% ethanol) the accumulation of phosphatidylethanol in cells permeabilized with beta-escin, a saponin-like detergent. Basal PLD activity was very low when cells were permeabilized and incubated in cytosol-like medium containing micromolar [Ca2+]. When this medium was supplemented with exogenous MgATP or guanosine 5'-[gamma-thio]triphosphate (GTP[S]), PLD activity increased by 9- and 14-fold respectively. Cells permeabilized in the absence of exogenously added MgATP, but in the presence of 1 microM vanadate/100 microM H2O2, also exhibited a modest 12-fold increase in PLD activity. However, the simultaneous presence of either GTP[S] plus exogenous MgATP or GTP[S] plus vanadate/H2O2 (and endogenous MgATP) induced similar 60-75-fold increases in the rate and extent of phosphatidylethanol accumulation. These latter effects of vanadate/H2O2 were strongly correlated with the very rapid accumulation of multiple tyrosine-phosphorylated proteins. Other studies utilized cells which were permeabilized in the presence of GTP[S] and then washed before assay of PLD. These cells retained approximately 60% of the MgATP-regulatable PLD activity (EC50 approximately = to 100 microM MgATP) observed in freshly permeabilized non-washed cells. In the absence of GTP[S] pre-treatment, washed cells retained minimal PLD activity. Genistein, a tyrosine kinase inhibitor, significantly attenuated the ability of MgATP to stimulate PLD activity and accumulation of tyrosine-phosphorylated proteins in the washed GTP[S]-treated cells. These data suggest that PLD activity in myeloid leucocytes involves co-ordinate regulation by both G-protein(s) and tyrosine phosphorylation.

72 citations

Journal ArticleDOI
TL;DR: This paper showed that vanadate is slightly more strongly adsorbed than phosphate on iron oxyhydroxide than vanadates on apatite, and vanadatate was coprecipitated by adding waste pickle liquor (FeCl 2 (aq)) plus further lime, with aeration to convert Fe(II) to Fe(III).

72 citations

Journal ArticleDOI
TL;DR: The electrogenic proton-translocating ATPase in the plasma membrane of Neurospora has been solubilized with lysolecithin and purified using a combination of gel filtration and density gradient centrifugation.

72 citations

Journal ArticleDOI
TL;DR: Pervanadate has the unique ability to markedly increase maximal cell responsiveness in stimulating glucose transport achieved at a saturating insulin concentration, suggesting a possible clinical application in the management of glucose uptake in pathological conditions of insulin resistance and hyperinsulinemia.
Abstract: Previous studies have shown that the combination of vanadate and H2O2 generates peroxide(s) of vanadate (pervanadate) that is able to mimic insulin in stimulating lipogenesis or protein synthesis and inhibiting lipolysis in rat adipocytes. Here we report that pervanadate is a potent trigger of 3-O-methylglucose transport in rat adipocytes, with an effective concentration of 5 microM and a maximum at 20 microM. Moreover, pervanadate produced an additional activation of approximately 60% on glucose influx in cells treated with maximally activating concentrations of insulin. Vanadate was ineffective in potentiating insulin-stimulated glucose uptake. Quercetin, a bioflavonoid that inhibits insulin receptor tyrosine kinase, blunted this effect of pervanadate. Treatment of adipocytes with pervanadate inhibited protein phosphotyrosyl phosphatase activity of cell extracts in a dose-dependent manner, with an ID50 of 5 microM and complete inhibition at 80 microM. In contrast, vanadate (1-800 microM) did not appreciably inhibit cell phosphotyrosyl phosphatases. The inhibitory effect of pervanadate correlated with the increase in protein phosphotyrosine accumulation, as determined by Western blotting with antiphosphotyrosine antibodies. The most prominent phosphotyrosine-containing band detected in pervanadate-treated adipocytes was that of autophosphorylated insulin receptor, identified by immunoblotting or immunoprecipitation with antiinsulin receptor antibodies. The addition of insulin to pervanadate-treated adipocytes (20 microM) caused a further increase (approximately 70%) in receptor autophosphorylation. In a cell-free system using partially purified insulin receptor devoid of tyrosine phosphatase activity, pervanadate did not stimulate the receptor autophosphorylation or interfere with the stimulating effect of insulin. These results suggest that 1) pervanadate triggers glucose uptake by increasing autophosphorylation of insulin receptor, preventing its dephosphorylation; 2) under physiological conditions, cellular protein phosphotyrosyl phosphatase activity is high, thereby significantly opposing insulin-mediated hexose transport; and 3) pervanadate has the unique ability to markedly increase maximal cell responsiveness in stimulating glucose transport achieved at a saturating insulin concentration. These findings suggest a possible clinical application in the management of glucose uptake in pathological conditions of insulin resistance and hyperinsulinemia.

72 citations


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