Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The purified ATP synthetase complex (F1F0) from Escherichia coli was adsorbed to immobilized poly-(L-lysine)-deoxycholic acid. About 0.7 mg F1F0 were bound per ml of settled gel. The hydrophilic F1 part was dissociated from the complex by treatment with 7 M urea. F0 was eluted in high yield either with deoxycholate (6 mM) or taurodeoxycholate (10 mM). About 14% of the total protein bound to the column was eluted as F0, which corresponds to 64% of the total F0 in the F1F0 complex. 2. The purified F0 preparation obtained was composed of three different kinds of subunits with apparent molecular weights of 24000 (a), 19000 (b) and 8300 (c), respectively as determined by sodium dodecyl sulfate gel electrophoresis. 3. After incorporation into liposomes and the generation of a potassium diffusion potential by valinomycin, the F0 preparation mediated H+ translocation. This H+ uptake is inhibited by either dicyclohexylcarbodiimide or purified F1 ATPase. 4. Incubation of F0-containing liposomes with F1 led to the reconstitution of an ATP-driven quenching of acridine-dye fluorescence. The quenching was abolished by uncoupler and prevented by dicyclohexylcarbodiimide.
 ...
PMID:ATP synthetase (F1F0) of Escherichia coli K-12. High-yield preparation of functional F0 by hydrophobic affinity chromatography. 629 Feb 12

The subcellular distribution of the Na+/H+ antiporter in renal proximal tubule cells was studied with differential and density gradient centrifugation. Enzyme markers for basolateral membranes [Na+/K+)-ATPase), brush border membranes (maltase), and a variety of intracellular organelles (NADPH cytochrome c reductase, thiamine pyrophosphatase, acid phosphatase, and succinate cytochrome c reductase) were simultaneously assayed in sucrose density gradients. Basolateral membranes (median rho = 1.150) were well separated from brush border membranes (median rho = 1.165) by this technique. Markers for other cellular organelles had intermediate or bimodal distributions. To determine the cellular location of the Na+/H+ antiporter, Na+-dependent collapse of preformed pH gradients was assayed in the sucrose density gradient fractions using acridine orange. Na+/H+ antiporter activity paralleled the distribution of the brush border membrane fractions; activity in the peak basolateral membrane fraction was less than 5% of that in the peak brush border fraction. To determine whether antiporter activity was potentially detectable in all cell fractions, nigericin was added to each fraction and K+/H+ exchange was assayed with acridine orange. Activity was present in all sucrose density gradient fractions. In addition, there was no alteration in Na+/H+ exchange activity measured in brush border membranes after mixing with cell sol or basolateral membranes, showing that neither inhibitors nor activators of the Na+/H+ antiporter were present in any of the cell fractions. These controls confirmed the finding that Na+/H+ antiporter activity was absent from basolateral membranes. The presence of the Na+/H+ antiporter in brush border membranes and its absence from basolateral membranes is consistent with its playing an important role in the vectorial transport of H+ from blood to tubular lumen in the renal proximal tubule.
 ...
PMID:Asymmetric distribution of the Na+/H+ antiporter in the renal proximal tubule epithelial cell. 631 99

1. The isolation of F0F1-ATPase complex from Rhodospirillum rubrum chromatophores by the use of taurodeoxycholate is described. 2. The enzyme preparation contains about 12 polypeptides; five are subunits of the F1 moiety. 3. The ATPase activity of the purified enzyme is dependent on the addition of phospholipids. 4. Km-vales for Mg2+-ATP and Ca2+-ATP are similar to the values obtained for the membrane-bound enzyme. 5. The F0F1-ATPase complex is more than 70% inhibited by oligomycin and N,N'-dicyclohexylcarbodiimide. 6. The F0F1-ATPase complex was integrated into liposomes. The reconstituted proteoliposomes catalyzed energy transduction as shown by ATP-dependent quenching of acridine dye fluorescence and ATP-32Pi exchange.
 ...
PMID:Energy-linked reactions catalyzed by the purified ATPase complex (F0F1) from Rhodospirillum rubrum chromatophores. 644 94

Exposure of isolated gastric mucosal surface cells to NH4+ results in acidification of cells as determined by a fluorescent dye technique using acridine orange. The resulting intracellular pH gradient is maintained when cells are suspended in either buffered HCO3- -free Ringer's or choline chloride solution. Cells suspended in a Na+-containing but K+-free solution exhibit dissipation of the proton gradient. When Na+ is added to cells suspended in Na+, K+-free solution, the gradient rapidly dissipates with a half-maximal response occurring at 56 mM Na+. The effect of Na+ is amiloride sensitive with half-maximal inhibition occurring at 38 microM at a Na+ concentration of 50 mM. The K+ does not cause dissipation of the gradient and neither ouabain nor valinomycin have an effect. Yet, K+ has a modulating influence on Na+/H+ exchange by the isolated surface cells. The addition of K+ to acid-loaded cells resuspended in Na+-free solution decreases the ability of subsequent Na+ addition to evoke gradient dissipation. The data suggest that Na+/H+ exchange appears to be at least one mechanism whereby gastric mucosal surface cells could protect themselves against diffusing acid. This ion exchange mechanism is amiloride sensitive and appears to be unrelated to Na+, K+ adenosine triphosphatase activity, but is affected by the external K+ concentration.
 ...
PMID:H+ disposal by rabbit gastric mucosal surface cells. 669 70

The purpose of the present study was to investigate the structure of muscle mitochondria for a possible early response to electrically induced short- and medium-term activity. Rats were anesthetized with Na-pentobarbital. Both parts of the triceps surae muscle were stimulated by direct electrical impulses for periods between 2 and 60 min. Biopsies were taken and prepared for histological, enzyme-histochemical, and electron-microscopic examinations. Enzyme histochemistry demonstrated an increase of oxidative activity and an increase of RNA by NADH-tetrazolium reductase and modified Gomori's trichrome staining or acridine orange-induced fluorescence, respectively. These changes appeared especially within type I fibers, as shown by ATPase reactions, and corresponded to an increase in number and size of muscle mitochondria, followed by alterations of the mitochondrial structure. The mitochondria reacted immediately to the electrical stimulation of the muscle, and the degree of alteration depended on the duration of the experiments. These results suggest that mitochondria have a certain capacity for adapting rapidly to changes in the energy metabolism. Beginning energetic decompensation may be responsible for the alterations of the mitochondrial structure.
 ...
PMID:Mitochondrial reaction in skeletal muscle to induced activity. 687 72

A method for the measurement of intravesicular pH of phospholipid vesicles and gastric microsomes is described. The present method makes use of the well characterized pH-dependent shift of the emission maximum of two fluorescent amines, quinine and acridine. As the probes distribute into the intravesicular space, according to the existing pH gradient, they respond to the acidic environment and emit fluorescence at a longer wavelength than the external probes which sense the more alkaline medium. By measuring both the decrease in the alkaline fluorescence peak and the enhancement of the acidic peak, direct determination of the internal pH can be obtained. This method has the advantages of giving a positive signal (enhancement of fluorescence instead of quenching), measuring intravesicular pH directly without the need of independent measurement of the volume of the H+ space, and also enabling the possible use of a much lower probe concentration than that required by the fluorescence-quenching method. The accuracy of the present method was quantitatively verified using phospholipid vesicles as a well defined model system. Application to biological systems was demonstrated using gastric microsomes which actively transport H+ into the microsomal space via an H+-K+ exchange ATPase system. The reasoning of the present method is also extended to the monitoring of internal alkaline pH gradient by using a fluorescent weak acid, o-hydroxycinnamic acid. Some general criteria for the future search for better Ph gradient probes are presented.
 ...
PMID:A novel method for measurement of intravesicular pH using fluorescent probes. 719 Aug 42

Adenosinetriphosphatase (ATPase) activity stimulated by K+ and inhibited by Sch-28080 (SCH), omeprazole (OME), and vanadate has been measured in microsomes from mammalian renal medulla and attributed to a kidney isoform of the H(+)-K(+)-ATPase. To determine whether the H(+)-K(+)-ATPase inhibitors could also inhibit the vacuolar (V)-type H(+)-adenosinetriphosphatase (H(+)-ATPase, i.e., H+ pump) in mammalian intracellular vesicles, we examined their effects on bafilomycin-sensitive acidification in renal cortical vesicles (CEV) and medullary endocytic vesicles (MEV). Rats were injected with fluorescein isothiocyanate-labeled dextran, and labeled endosomes were enriched from kidney tissue homogenates by differential and Percoll density gradient centrifugation. In the CEV, the V-type H+ pump was inhibited 25% by SCH and 30% by OME (100 microM each). Whereas the inhibition by OME was concentration and time dependent, the inhibition by SCH was only concentration dependent. Inhibition by these compounds was similar in the presence of 50 mM K+ (in = out) and in the complete absence of K+, thus ruling out a significant involvement of H(+)-K(+)-ATPase-mediated acidification. Inhibition, however, was not observed with 10 microM SCH and OME. The sensitivity of the V-type H+ pump to 100 microM SCH and OME in CEV was confirmed by the comparable inhibitions of intravesicular acidification observed in acridine orange fluorescence quench studies and by inhibition of Pi liberation in an ATPase assay. We also found that the V-type H+ pump in isolated rat liver endosomes is sensitive to 100 microM SCH and OME to a similar degree. In the MEV, acidification was only weakly affected by 100 microM SCH and OME, thus suggesting that H(+)-ATPases in endosomes from cortical and medullary tubules are different, possibly due to a previously described selective expression of subunit isoforms. Our finding indicates the importance of using low concentrations (< 10 microM) of OME and SCH in studies of H(+)-K(+)-ATPase in nongastric tissues to avoid misinterpretation of the data due to nonspecific inhibition of V-type H(+)-ATPases.
 ...
PMID:H(+)-ATPases of renal cortical and medullary endosomes are differentially sensitive to Sch-28080 and omeprazole. 751 42

The mechanisms of proton secretion by the proximal brush-border membrane (BBM) were compared in carnivorous (dog), omnivorous (human, pig, rat), and herbivorous (rabbit, hamster) species. The activity of the proton pump (V-type bafilomycin-sensitive H(+)-adenosinetriphosphatase) and of the Na+/H+ exchanger (amiloride-sensitive quenching of acridine orange fluorescence), the two major proton secretion mechanisms, was measured. The enzymatic activity of the H(+)-adenosinetriphosphatase activity was measured in intact (endosomes) and solubilized (0.1% deoxycholate or Triton X-100) BBM vesicles isolated by conventional Mg2+ precipitation techniques. In all species, but not in humans, the fraction of the ATP turnover energizing the proton pump (bafilomycin-sensitive respiration) was also measured in isolated proximal tubules. Significant differences in acid transport mechanisms were noted between species, with the proton pump predominating in the BBM of carnivorous species and the Na+/H+ exchanger predominating in the BBM of herbivorous species. The fraction of respiration suppressible by bafilomycin in proximal tubules was also different in all the species considered. This may indicate a different organization of proximal H+ transport related to the species-specific menace to acid-base balance.
 ...
PMID:Mechanisms of proximal proton secretion in BBM of herbivorous, omnivorous, and carnivorous species. 763 82

Destruxin B, a peptide antibiotic, inhibits vacuolar-type ATPase (V-ATPase) specifically and dose-dependently among ATPases examined. Acidification of intracellular organelles is also blocked by destruxin B at comparable concentrations when assessed by accumulation of acridine orange. The inhibitory activity of destruxin B is weaker than that of bafilomycin A1 and folimycin, well known macrolide inhibitors of V-ATPase, when compared at the same molar concentration. Unlike the macrolide antibiotics, however, the inhibitory activity of destruxin B is readily reversible. This novel feature of destruxin B should make it a useful probe in the analysis of V-ATPase function in cell physiology.
 ...
PMID:Destruxin B, a specific and readily reversible inhibitor of vacuolar-type H(+)-translocating ATPase. 780 70

Guanosine 5'-triphosphate (GTP)-binding proteins (G proteins) are expressed in a heterogeneous manner in the mammalian kidney. In particular, cells of the medullary collecting tubule demonstrate a complex pattern of G protein expression both between cell types and between the polarized surfaces of individual cells. Intercalated cells expressing the H(+)-ATPase are also prevalent in this nephron segment. To examine interactions between G proteins and the H(+)-ATPase, we performed immunocytochemical studies on perfusion-fixed sections of rat kidney using polyclonal anti-G protein antibodies and E11, a mouse monoclonal antibody to the 31-kDa subunit of the vacuolar H(+)-ATPase. G alpha s subunits were consistently not associated with cells containing the H(+)-ATPase in this nephron segment, whereas G alpha i-2, G alpha i-3, and G alpha q/11 were. Some intercalated cells that stained prominently for the proton pump in the apical membrane did not, however, stain for any G protein alpha-subunit. We prepared medullary membrane vesicles highly enriched for the H(+)-ATPase to examine possible functional interactions of G proteins with the H(+)-ATPase by the acridine orange method. These vesicles were also highly enriched for G protein subunits. Proton transport was significantly increased in the presence of guanosine 5'-O-(3-thiotriphosphate), and this held true in the absence of chloride. This excludes an effect on chloride conductance indirectly stimulating the H(+)-ATPase. Guanine nucleotides did not affect the proton leak of the vesicles. Thus some G proteins are associated with the H(+)-ATPase and can regulate its function; however, the particular G proteins involved remain to be identified.
 ...
PMID:Association and interactions of GTP-binding proteins with rat medullary H(+)-ATPase. 781 Jul 2


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>