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)

This review has attempted to cover some of the findings that have been made in the mechanism of gastric secretion in recent years. It is hard to offer any firm conclusions, whether at the level of stimulus, metabolism, or the terminal process of secretion. However, some generalizations may be possible. At least amphibian gastric secretion is stimulated by cAMP as a second messenger, with histamine presumably acting as the primary messenger. The resultant metabolic change is due largely to a direct stimulation of catabolism, which in dog appears to be the metabolism of hexose, through the glycolytic process, the hexose monophosphate shunt, and the Krebs' cycle with cytoplasmic reduction and mitochondrial oxidation of pyridine nucleotides. No evidence could be obtained for changes in high energy phosphate or for lipolysis. One would expect gastric mucosal membranes during secretion to contain an anion-restricted electrogenic H+ pump, but they in fact contain an ATPase stimulated by monovalent cations and are insensitive to ouabain. In addition, hog or dog gastric membranes have the vectorial properties of H+ absorption, Rb+ extrusion, and ANS fluorescence enhancement with the addition of ATP, as well as protein phosphorylation by 32P dependent on a K+ gradient.
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PMID:Gastric secretion. 1 82

The structural consequences of ouabain interaction with a highly purified Na+K+-ATPase preparation, isolated from the outer medulla of porcine kidneys, were examined. The apparent heat capacity vs. temperature profile of the enzyme was obtained with a newly designed differential scanning calorimeter. The profile was characterized by a major endothermic transition at 55.3 degrees C. This transition appeared to correspond to irreversible protein denaturation since it was associated with loss of enzyme activity and the transition was not present in claorimetric profiles obtained after the initial scan of a sample. Interaction of ouabain with its receptor surface on the Na+, K+-ATPase shifted the endothermic transition from 55.3 to 59.5 degrees C and decreased the width of the transition. This indicated that the ouabain-Na+, K+-ATPase complex was more stable with respect to temperature and that the apparent cooperative nature of the transition was greater for the complex than for the untreated enzyme. The effects of the ouabain-enzyme interaction were examined with the fluorescence probe, 8-anilino-1-naphthalenesulfonic acid. The fluorescence of this dye in the presence of the enzyme was monitored as a function of temperature. These measurements also suggested that ouabain induces the formation of a more stable enzyme conformation. Incubation of the enzyme for 10 min at 53 degrees C with and without ouabain and measurement of remaining enzyme activity after the dissociation of bound ouabain confirmed the conclusions from the fluorescence and scanning calorimeter experiments.
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PMID:Detection of a ouabain-induced structural change in the sodium, potassium-adenosine triphosphatase. 13 34

The interaction of myosin subfragment-1 (S-1) with 4,4'-bis(1-anilinonaphthalene 8-sulfonate) (bis-ANS) has been studied by monitoring the fluorescence of the latter when the two components form a complex. Because ATP and ATP analogs partially displace complexed bis-ANS it has also been possible to study interactions of S-1 and nucleotides by using the displacement effect. Approximate values of the parameters of these various interactions have been measured. Some possible applications of bis-ANS have been explored. For example, it provides a very convenient method for obtaining the Michaelis constant, Km, in steady-state S-1 nucleoside triphosphatase; this particular application has also provided some evidence for inferring that in Ca2+ (but not in Mg2+) adenosinetriphosphatase (ATP phosphohydrolase, EC 3.6.1.3) S-1 behaves like a mixture of two components, each with its own Km. Clear energy transfer occurs between tryptophan residues and bound bis-ANS. The fluorescence also suggests that S-1 undergoes some slow relaxations following substrate binding.
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PMID:4,4'-Bis (1-anilinonaphthalene 8-sulfonate) (bis-ANS): a new probe of the active site of myosin. 26 28

A single X-ray irradiation of the rabbit hindlimbs in a dose of 0.24 C/kg evokes a decrease in fluorescence of the ANS probe bound with membranes of the sarcoplasmatic reticulum as a result of the decrease of binding sites, binding constant as well as the quantum output of the probe. A decrease in fluorescence of tryptophan residues of Ca-ATPase localized in membranes and attenuation of interaction of its SH-group with dithionitrobenzoic acid has been also observed at early postradiation terms (1 and 24 h). The obtained results evidence for structural rearrangements occurring in membranes of the sarcoplasmic reticulum under the effect of ionizing radiation. Changes in conformation of CA-ATPase molecules contribute much to this process.
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PMID:[Structural changes in the sarcoplasmic reticulum membrane of skeletal muscles at the early stage of x-ray irradiation]. 183 69

Ca2(+)-ATPase activity in human red cell membranes is dependent on the presence of calmodulin. All trans-retinoic acid inhibited human red cell membrane Ca2(+)-ATPase activity in vitro in a concentration-dependent manner (10(-8) to 10(-4) M). In contrast, retinol, retinal, 13-cis-retinoic acid and the benzene ring analogue of retinoic acid did not alter enzyme activity. Purified calmodulin (up to 500 ng/ml, 3 X 10(-8) M) added to red cell membranes, in the presence of inhibitory concentrations of retinoic acid, only partially restored Ca2(+)-ATPase activity. 125I-Calmodulin bound to red cell membranes was displaced by unlabeled retinoic acid (50% reduction at 10(-8) M retinoic acid), as effectively as by unlabeled calmodulin. Another calmodulin-stimulable enzyme, bovine brain cyclic nucleotide phosphodiesterase, was unaffected by retinoic acid. 8-Anilino-1-naphthalene sulfonic acid bound to calmodulin, studied spectrofluorometrically, was not displaced by retinoic acid. Thus, retinoic acid inhibits calmodulin binding to red cell membranes, reducing calmodulin-stimulable Ca2(+)-ATPase activity. Retinoic acid does not directly interact with calmodulin, but rather exerts its effect by interfering with calmodulin access to the membrane enzyme. These effects occur at physiological concentrations of the retinoid.
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PMID:Retinoic acid inhibits calmodulin binding to human erythrocyte membranes and reduces membrane Ca2(+)-adenosine triphosphatase activity. 216 34

Recent studies of cellular T4 and T3 uptake have indicated active transport of the hormones into the cell rather than passive diffusion of the non-protein bound fraction. In order to study the significance of the extracellular environment, oxygen consumption and glucose uptake were examined in human mononuclear blood cells. Cells were incubated in protein free medium and in human serum totally depleted of thyroid hormones by resin treatment and fixed amounts of T4 (total T4 = 0-50-100-5000 nmol/l; free T4 = 0-5-11-5600 pmol/l) were added. Thyroxine stimulated glucose uptake and oxygen-consumption in a dose dependent manner but the T4 stimulation was dependent on the total concentration of T4 and did not differ between serum incubation or non-protein containing medium. Addition of ANS (100 mg/l) which inhibits binding of T4 to TBG, did not increase T4 effect in serum. Inhibition of the NaK-ATPase by addition of ouabain (9-72 mg/l) did not inhibit T4 stimulation, thus indicating that the ouabain sensitive NaK-ATPase is not a major component of the processes which initiate the intracellular effects of T4. Therefore the stimulation of uptake of oxygen and glucose in human mononuclear blood cells seems to be dependent on the total concentration of T4 and not on the non-protein bound (free) fraction suggesting active membrane uptake of T4, as the limiting factor for intra-cellular hormone effect.
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PMID:Effect of thyroxine on cellular oxygen-consumption and glucose uptake: evidence of an effect of total T4 and not "free T4". 225 36

A decrease in activity of Ca2(+)-ATPase and activation of Na+, K(+)-ATPase, correlating with elevation in content of phosphatidyl inositol and phosphatidyl serine, were detected in erythrocyte membranes of patients with the infectional-allergic form of bronchial asthma. Microviscosity of the erythrocyte membranes, estimated by fluorescence spectra of pyrene, was not altered, while negative charge as shown by ANS- fluorescence, was slightly increased on the membrane surface. Euphylline, intal, levamizole and glucocorticosteroid were found to regulate the ATPases activity in vivo and in vitro.
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PMID:[Structural-functional properties of erythrocyte membranes in patients with infectious-allergic bronchial asthma]. 253 46

Fluorescence energy transfer measurements have been performed to investigate the distances between the FITC-binding site in the (Ca2++Mg2+)-ATPase from sarcoplasmic reticulum and 8-aniline-1-naftalenesulfonate (ANS-) and diphenylhexatriene (DPH) localized in different sites of the membrane. The distances calculated between FITC bound to the ATPase and ANS- and DPH in the membrane, were approx. 51 A and 60 A, respectively.
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PMID:Distances between the FITC-binding site in the (Ca2++Mg2+)-ATPase from sarcoplasmic reticulum and fluorescent probes located in the membrane. 295 53

On days 7 and 15 after gamma-irradiation (4 Gy) changes were noted in the temperature dependence of the erythrocyte suspension viscosity coefficient, in the electrolyte composition of the abdominal aorta, plasma, and erythrocytes, in Na, K- and Mg-ATPase activity, and in the intensity of fluorescence of 1.8 ANS of erythrocyte ghost of albino rats. The changes were a function of the stage of radiation sickness and were more pronounced on the 15th day following irradiation.
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PMID:[The effect of ionizing radiation on the blood plasma and erythrocytes and on the wall of the abdominal aorta of rats]. 297 24

(Na+ + K+)-ATPase from shark rectal glands reconstituted into lipid vesicles and oriented inside out catalyses an ouabain-sensitive Na+-Na+ exchange in the absence of intravesicular K+ when ATP is added extravesicularly. Intravesicular ouabain inhibited the exchange completely. This was also the case with digitoxigenin added to the vesicles. Intravesicular oligomycin inhibited the Na+-Na+ exchange partly in a fashion which was ATP dependent. The exchange is accompanied by a net hydrolysis of ATP with an apparent Km of 2.5 microM. ADP was found to give no stimulation of the Na+-Na+ exchange, contrarily, ADP inhibited the ATP-dependent exchange of Na+ both at optimal and supraoptimal ATP concentrations. When initial influx and efflux of 22Na was measured and the hydrolysis of ATP concomitantly determined a coupling ratio of 2.8:1.3:1 was found, i.e. 2.8 moles of Na+ were taken up (cellular efflux) and 1.3 moles of Na+ extruded (cellular influx) for each mole of ATP hydrolyzed. The electrogenic Na+-Na+ exchange generated a transmembrane potential which was measured with the fluorescent probe ANS (8-anilino-1-naphthalenesulfonic acid) to be 60 mV positive inside the liposomes (extracellular).
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PMID:Na+-Na+ exchange mediated by (Na+ + K+)-ATPase reconstituted into liposomes. Evaluation of pump stoichiometry and response to ATP and ADP. 299 89


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