Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of a single administration of lead nitrate on the activity of gamma-glutamyltranspeptidase (gamma-GT), adenosine triphosphatase (ATPase), the placental form of glutathione S-transferase (GST-P) and adenylate cyclase (AC), four enzymes widely used as phenotypic markers for preneoplasia, was investigated in the liver of male Wistar rats. The results of the histochemical enzymatic staining indicated that an acute treatment with lead nitrate induces the activity of gamma-GT, mainly in the hepatocytes located around zone I of the liver acinus, with a maximum seen between 72-96 hours. On the other hand, the activity of ATPase was found to be severely inhibited at 2-3 days after treatment, as shown by a strong decrease in the staining of the bile canaliculi of zones II and III. Immunohistochemical analysis revealed that lead nitrate administration also resulted in the appearance in most of the hepatocytes of GST-P, an enzyme whose activity is almost undetectable in normal rat liver, but is elevated in preneoplastic liver lesions. Finally, lead nitrate treatment resulted in an inhibition of AC activity which was maximal after 24 hours.
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PMID:Modulation of the activity of hepatic gamma-glutamyl transpeptidase, adenosine triphosphatase, placental glutathione S-transferase and adenylate cyclase by acute administration of lead nitrate. 290 38

Activation of ribulose bisphosphate carboxylase/oxygenase (rubisco) in vivo is mediated by a specific protein, rubisco activase. In vitro, activation of rubisco by rubisco activase is dependent on ATP and is inhibited by ADP. Purified rubisco activase hydrolyzed ATP with a specific activity of 1.5 mumol min-1 mg-1 protein, releasing approximately stoichiometric amounts of ADP and Pi. Hydrolysis was highly specific for ATP-Mg and had a broad pH optimum, with maximum activity at pH 8.0-8.5. ATPase activity was inhibited by ADP but not by molybdate, vanadate, azide, nitrate, or fluoride. Addition of rubisco in either the inactive or activated form had no significant effect on ATPase activity. Incubation of rubisco activase in the absence of ATP resulted in loss of both ATPase and rubisco activation activities. Both activities were also heat labile, with 50% loss in activity after 5 min at 38 degrees C and complete inhibition following treatment at 43 degrees C. Both activities showed a sigmoidal response to ATP concentration, with half-maximal activity at 0.053 mM ATP. Rubisco activation activity was dependent on the concentrations of both ATP and ADP. The results suggest that ATPase activity is an intrinsic property of rubisco activase.
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PMID:Adenosine triphosphate hydrolysis by purified rubisco activase. 291 85

Extracellular ATP rendered the plasma membrane of transformed mouse fibroblasts permeable to normally impermeant molecules. This permeability change was prevented by increasing the ionic strength of the isotonic medium with NaCl. Conversely, the cells exhibited increased sensitivity to ATP when the NaCl concentration was decreased below isotonicity, when the KCl concentration was increased above 5 mM while maintaining isotonicity, and when the pH of the medium was raised above 7.0. These conditions as well as the addition of ATP itself caused cell swelling. However, the effect of ATP was independent of cell volume and dependent upon the ionic strength and not the osmolarity of the medium since 1) addition of sucrose to isotonic medium did not prevent permeabilization although media made hypertonic with either sucrose or NaCl caused a decrease in cell volume; and 2) addition of sucrose or NaCl to hypotonic media caused a decrease in cell volume, but only NaCl addition decreased the response to ATP. Conditions that have been shown to inhibit plasma membrane proteins that play a reciprocal role in cell volume regulation had reciprocal effects on the permeabilization process, even though the effect of ATP was independent of cell volume. For example, inhibition of the Na+,K+-ATPase by ouabain increased sensitivity of cells to ATP while conditions which inhibit Na+,K+,Cl- -cotransporter activity, such as treatment of the cells with the diuretics furosemide or bumetanide or replacement of sodium chloride in the medium with sodium nitrate or thiocyanate, inhibited permeabilization. The furosemide concentration that inhibited permeabilization was greater than the concentration that inhibited Na+,K+,Cl- -cotransporter-mediated 86Rb+ (K+) uptake, suggesting that the effect of furosemide on the permeabilization process may not be specific for the Na+,K+,Cl- -cotransporter.
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PMID:Ionic dependence of the extracellular ATP-induced permeabilization of transformed mouse fibroblasts: role of plasma membrane activities that regulate cell volume. 291 39

Purified goblet cell apical membranes from Manduca sexta larval midgut exhibit a specific ATPase activity approx. 20-fold higher than that in the 100 000 X g pellet of a midgut homogenate. The already substantial ATPase activity in this plasma membrane segment is doubled in the presence of 20-50 mM KCl. At ATP concentrations ranging from 0.1 to 3.0 mM, the presence of 20 mM KCl leads to a 10-fold increase in the enzyme's affinity for ATP. ATPase activity is greatest at a pH of approx. 8. In addition to ATP, GTP serves as a substrate, but CTP, ADP, AMP and p-nitrophenyl phosphate do not. Either Mg2+ or Mn2+ is required for activity and cannot be replaced by Ca2+ or Zn2+. The ATPase activity of goblet cell apical membranes is inhibited by neither the typical (Na+ + K+)-ATPase inhibitors, ouabain and orthovanadate, nor by the typical mitochondrial F1F0-ATPase inhibitors, azide and oligomycin. Although 1.5 microM DCCD is ineffective, 150 microM DCCD leads to total inhibition of ATPase activity. The ATPase activity of goblet cell apical membranes is stimulated not only by K+, but also, in order of decreasing effectiveness, by Rb+, Li+, Na+ and even Mg2+. Replacement of Cl- by Br-, F- and HCO3- has less influence than variation of the cations. However, replacement of Cl- by NO3- inhibits strongly this ATPase activity. The ATPase activity described above is characteristic of the alkali metal ion pump containing apical membranes of goblet cells and is not enhanced to a similar degree in other purified midgut epithelial cell plasma membrane segments. Its localization, its broad cation specificity and its insensitivity to ouabain all mimic properties of active ion transport by the lepidopteran midgut and suggest this ATPase as a possible key component of the lepidopteran electrogenic alkali metal ion pump.
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PMID:Cation-stimulated ATPase activity in purified plasma membranes from tobacco hornworm midgut. 293 79

Thermoacidophilic archaebacteria have gained much interest because of their phylogenetic distance to eubacteria and eukaryotes and also because of their unique living conditions. Investigation of the energy-converting system therefore offers a key for understanding the evolutionary position and environmental adaptation of these unusual bacteria. A plasma-membrane-associated adenosine triphosphatase with specific activities of 0.3-0.6 mumol min-1 (mg protein)-1 has been detected in the thermoacidophilic archaebacterium Sulfolobus acidocaldarius (DSM 639). The enzyme exhibits two optima at pH 5.5 and 8.0, sulfite activation leads to only one optimum at pH 6.25. In the presence of the divalent cations Mg2+ or Mn2+ it hydrolyzes ATP with highest reactivity and also other purine and pyrimidine nucleotides, but not ADP and pyrophosphate. A specific stimulation by monovalent cations is not observed. The ATPase activity is not inhibited by N,N'-dicyclohexylcarbodiimide, azide or vanadate, but it is by the vascular ATPase inhibitor nitrate with an [I]50 of 8 mM. Linear Arrhenius plots up to 75 degrees C reflect pronounced adaptation to the hot environment of the archaebacterium. The solubilized ATPase as localized by activity staining in non-denaturating gels and further analyzed by sodium dodecyl sulfate electrophoresis is composed of two major polypeptides of 65 and 51 kDa reminiscent of the alpha and beta subunits of eubacterial and eukaryotic F0F1-ATPases. The ATPase is suggested as a probable candidate for a reversibly acting ATP synthase responsible for oxidative phosphorylation found in Sulfolobus acidocaldarius.
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PMID:A plasma-membrane associated ATPase from the thermoacidophilic archaebacterium Sulfolobus acidocaldarius. 295 1

Anion dependence of (Ca2+ + K+)-stimulated Mg2+-dependent transport ATPase and its phosphorylated intermediate have been characterized in both "intact" and "broken" vesicles from endoplasmic reticulum of rat pancreatic acinar cells using adenosine 5'-[gamma-32P] triphosphate ([gamma-32P]ATP). In intact vesicles (Ca2+ + K+)-Mg2+-ATPase activity was higher in the presence of Cl- or Br- as compared to NO3-, SCN-, cyclamate-, SO4(2-) or SO3(2-). Incorporation of 32P from [gamma-32P]ATP into the 100-kDa intermediate of this Ca2+ATPase was also higher in the presence of Cl-, Br-, NO3- or SCN- as compared to cyclamate-, SO4(2-) or SO3(2-). When the membrane permeability barrier to anions was abolished by breaking vesicle membrane with the detergent Triton X-100 (0.015%) (Ca2+ + K+)-Mg2+ATPase activity in the presence of weakly permeant anions, such as SO4(2-) and cyclamate-, increased to the level obtained with Cl-. However, 32P incorporation into 100-kDa protein was still higher in the presence of Cl- as compared to cyclamate-, indicating a direct effect of Cl- on the Ca2+ATPase molecule. The anion transport blocker 4,4-diisothiocyanostilbene-2,2-disulfonate (DIDS) inhibited (Ca2+ + K+)-Mg2+ATPase activity to about 10% of the Cl- stimulation level, irrespective of the sort of anions present in both intact and broken vesicles. This indicates a direct effect of DIDS on (Ca2+ + K+)-Mg2+ATPase. K+ ionophore valinomycin influenced (Ca2+ + K+)-Mg2+ATPase activity according to the actual K+ gradient: Ko+ greater than Ki+ caused inhibition, Ko+ less than Ki+ caused stimulation. From these results we conclude that Ca2+ transport into endoplasmic reticulum is coupled to ion movements which must occur to maintain electroneutrality.
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PMID:Anion dependence of Ca2+ transport and (Ca2+ + K+)-stimulated Mg2+-dependent transport ATPase in rat pancreatic endoplasmic reticulum. 295 52

Male Wistar rats were exposed to 0.4, 1.2 and 4.0 ppm NO2 for 13 weeks to examine the effects of NO2 on the blood nitrate concentration and the Na+,K+-ATPase activity of red blood cells. Exposures to 1.2 and 4.0 ppm NO2 caused an elevation of the blood nitrate level at the first, third and eighth week. The maximum concentration attained was 148% (P less than 0.001, at the third week) and 201% (P less than 0.001, at the eighth week) of the controls at 1.2 and 4.0 ppm NO2, respectively. On the other hand, the nitrate concentration was decreased to the control level at the second, fourth and thirteenth weeks. 0.4 ppm NO2 caused a progressive but slight increase in the blood nitrate concentration from the third week and reached the maximum (122% of the control, P less than 0.001) at the eighth week. The Na+,K+-ATPase activity decreased slightly from the first week upon exposure to 4.0 ppm NO2 and reached the minimum (72% of the control, P less than 0.05) at the third week. Subsequently, the activity was increased to 159% (P less than 0.001) of the control at the eighth week. Exposure to 0.4 and 1.2 ppm NO2 caused fundamentally similar but less significant alterations of the Na+,K+-ATPase activity.
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PMID:In vivo effects of nitrogen dioxide on the blood nitrate level and the Na+,K+-ATPase activity of red blood cells of rats. 298 58

In HeLa cells two different types of mutants resistant to the cardiac glycoside ouabain (OuaR mutants) or erythrophleum alkaloid cassaine (CasR mutants) have been obtained. One type of mutants resistant to these compounds (designated as group A) are highly resistant (between 50 and 2000-fold) to various cardiac glycosides and their genins such as ouabain, oleandrin, digitoxin, digitoxigenin, strophanthidin, convallatoxin, gitoxin, gitoxigenin, gitaloxin, bufalin, and digoxigenin, but exhibit no cross-resistance to SC4453, a digoxin analog which contains a pyridazine ring in place of the lactone ring in the C-17 position. The second type of mutants (group B) exhibit cross-resistance to all of the cardiac glycosides including SC4453, but their level of resistance is at least 5-10-fold less than that of group A mutants. Interestingly, both groups of mutants exhibited similar degree of cross-resistance towards digoxin and actodigin (AY22241), indicating some differences in their behavior from other cardiac glycosides. Both classes of mutants exhibit no cross-resistance to a wide variety of other structurally and functionally related compounds, e.g. sanguinarine nitrate, ethacrynic acid, penicillic acid, veratridine, harmaline hydrochloride, 5,5'-diphenylhydantoin, quindonium bromide, methyl quinolizinum bromide, estradiol 17 beta-acetate, 21-acetoxy-pregnenolone, vanadium pentoxide, digitonin, and adriamycin, indicating that the genetic lesions in both groups of mutants are specific for cardiac glycosides. This inference is supported by the observation that both group A and B mutants show reduced binding of [3H]ouabain. In group A mutants, a part of the Na+/K+-ATPase activity is highly resistant to inhibition by ouabain, indicating that the genetic lesion in these mutants directly affects Na+/K+-ATPase. In contrast, the Na+/K+-ATPase from the group B mutants showed similar resistance towards ouabain and SC4453 as observed for the parental HeLa cells, indicating that these mutants are affected in a cellular component, other than Na+/K+-ATPase, which is involved in the interaction of cardiac glycosides with the cells. The lack of cross-resistance of the group A mutants to SC4453 and normal sensitivity of their Na+/K+-ATPase to this compound provides strong evidence that the mechanism of interaction of SC4453 with Na+/K+-ATPase differs from that of other cardiac glycosides.
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PMID:Cross-resistance and biochemical studies with two classes of HeLa cell mutants resistant to cardiac glycosides. The unusual behavior of cardenolide SC4453. 298 35

Ethacrynic acid (EA) highly sensitive Mg2+-ATPase activity was demonstrated in rat brain microsomes. Marker enzyme studies suggested that the EA highly sensitive Mg2+-ATPase activity originated mainly from plasma membranes, and possibly from synaptic vesicles. Oligomycin did not affect the EA highly sensitive Mg2+-ATPase activity. Sulfhydryl reagents, such as N-ethylmaleimide and 5,5'-dithiobis-(2-nitrobenzoic acid), and anion transport inhibitors, such as 4-acetamide-4'-isothiocyanostilbene-2,2'-disulfonic acid, 4,4'-diisothiocyano-stilbene-2,2'-disulfonic acid and 2,4-dinitro-1-fluorobenzene, completely inhibited the EA highly sensitive Mg2+-ATPase activity with apparent Ki values at 5, 5, 8, 8 and 10 microM respectively. Treatment of microsomes with ethylenediaminetetraacetic acid and ammonium sulfate increased the EA highly sensitive Mg2+ and Na+,K+-ATPase activities, but not EA less sensitive Mg2+- or HCO3-ATPase activity, 2- to 3-fold that in crude microsomes. Relative substrate specificities of ATP much greater than GTP greater than ITP greater than UTP, CTP, a Km for ATP at 0.77 mM, and an optimal pH at pH 7.4 were observed. Among the anions tested (Cl-, Br-, F-, HCO3-, I-, SCN-, NO3-), EA highly sensitive Mg2+-ATPase activity was stimulated significantly by Cl- and reduced by NO3-. These data suggest that a novel, plasma membrane-located and anion-sensitive Mg2+-ATPase activity exists in the brain.
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PMID:Novel microsomal anion-sensitive Mg2+-ATPase activity in rat brain. 298 56

Transport of D-glucose, p-aminohippurate and tetraethylammonium has been studied using renal brush border membrane vesicles isolated from rats with uranyl nitrate-induced acute renal failure (ARF). Initial rate and overshoot magnitude of Na+ gradient-dependent D-glucose uptake were decreased in brush border membrane vesicles from ARF rats compared with normal rats, although there was no significant difference on D-glucose uptake in the presence of equilibrated Na+ between normal and ARF rats. Uptake of p-aminohippurate by membrane vesicles from ARF rats did not differ from normal membrane vesicles. Uptake of tetraethylammonium with or without an H+ gradient was decreased in membrane vesicles from ARF rats compared with normal rats. Dissipation rate of H+ gradient across brush border membranes did not differ between both groups. In vitro incubation of normal brush border membrane vesicles with uranyl nitrate caused no alteration in any substrate transport. However, enzyme activities such as (Na+ + K+)-adenosine triphosphatase in renal cortical homogenate were inhibited markedly in the presence of uranyl nitrate. These results suggest that uranyl nitrate-induced ARF caused alterations in the transport properties of renal brush border membranes and that these transport dysfunctions were not due to the direct effect of uranyl nitrate, but could be secondarily induced after the impairment of the integrity for tubular cells.
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PMID:Transport of p-aminohippurate, tetraethylammonium and D-glucose in renal brush border membranes from rats with acute renal failure. 298 96


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