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.

Vanadate induction of L-type pyruvate kinase mRNA in adult rat hepatocytes in primary culture.

Abstract: In primary culture of adult rat hepatocytes, vanadate in the presence of glucose stimulates the expression of the liver (L-type) pyruvate kinase gene. Glucose by itself was inactive, and vanadate, like insulin, was also inefficient in the absence of glucose. Similar results were obtained on glucokinase gene expression. An analogue of cAMP, 8-(4-chlorophenylthio)-cAMP, inhibited the production of L-type pyruvate kinase and glucokinase mRNAs in the presence of glucose plus vanadate.

Modes of proton translocation across the cell membrane of respiring cyanobacteria

Abstract: Acidification of weakly buffered suspensions of the cyanobacteria Anacystis nidulans, Nostoc sp. strain MAC, Dermocarpa sp. and Anabaena variabilis was observed after the application of oxygen pulses to anaerobic cells. The acidification was caused by proton extrusion from the oxygen pulsed cells since it was eliminated by the uncoupler (H+ ionophore) carbonyl cyanide m-chlorophenylhydrazone. Results with the inhibitors dicyclohexylcarbodiimide or 7-chloro-4-nitrobenz-2-oxa-1,3-diazole, orthovanadate and cyanide indicated the association of various fractions of the observed proton extrusion with different activities of the cell membrane, viz. a H+-translocating reversible F0F1-ATPase, a unidirectional H+-translocating ATP hydrolase, and a respiratory electron transport system, respectively. Further parameters investigated were the pH dependence and the H+/O stoichiometry of the H+ extrusion from oxygen pulsed cyanobacteria. H+/O ratios at neutral pH were between 4 (Anacystis nidulans) and 0.3 (Dermocarpa) with uninhibited, actively phosphorylating cells and between 2 (Anacystis nidulans) and 0.4 (Dermocarpa) with ATPase-inhibited (ATP-depleted) cells, respectively. It is significant that with all four cyanobacteria tested a major fraction of the observed H+ ejection remained unaffected by ATPase inhibitors even at concentration which completely abolished all oxidative phosphorylation. Vanadate had a major effect on the H+ extrusion from Anabaena only. From this it is concluded that in the cyanobacterial species investigated part of the H+ extrusion from oxygen pulsed cells is directly linked to some H+-translocating respiratory electron transport chain present in the cell membrane.

Effects of vanadate on MgATP stimulation of Na-Ca exchange support kinase-phosphatase modulation in squid axons.

Abstract: We have proposed that in squid axons MgATP stimulation of Na-Ca exchange involves a phosphorylation-dephosphorylation process catalyzed by a kinase-phosphatase system. In the present work, we used ...

Transport Properties of the Tomato Fruit Tonoplast : I. Identification and Characterization of an Anion-Sensitive H-ATPase.

Abstract: An anion-sensitive H+-translocating ATPase was identified in membrane vesicles isolated from mature green tomato (Lycopersicon esculentum) fruit. The H+-ATPase was associated with a low density membrane population having a peak density of 1.11 grams per cubic centimeter, and its activity was inhibited by NO3−, N,N′-dicyclohexylcarbodiimide and diethylstilbestrol but not by vanadate, azide, molybdate, or oligomycin. This H+-ATPase has an unusual pH dependence indicating both a slightly acidic and a near neutral peak of activity. Chloride was found to be a potent stimulator of ATPase activity. The Km for the H+-ATPase was approximately 0.8 millimolar ATP. The characteristics of this H+-ATPase are very similar to those described for a number of plant cell tonoplast H+-ATPases suggesting that the activity identified in tomato fruit membranes is tonoplast-associated. This report demonstrates the feasibility of isolating tonoplast vesicles from acidic fruit tissues for studies of transport activities associated with fruit development and maturation.