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)

Spectrophotometric and fluorometric techniques were used to monitor the proportion of reduced to oxidized cytochrome (cyt) and levels of reduced pyridine nucleotide in preparations of whole toad brain in vitro. In resting, well-oxygenated brain, levels of reduction for cyt a3 ranged between 5% and 23%; for cyt a, 17-23%; for cyt c, 18-32%, and for cyt b, 25-42%. These levels of reduction cannot be due to functional hypoxia since hemoglobin in resting brains is 100% oxygenated. In brains treated with 10(-4) M ouabain, stimulant of brain respiration, the cytochromes first become more oxidized, then more reduced; ultimately there is a tendency to return to the initial levels of reduction. In brains bathed with solutions containing 30 mM potassium, also a stimulant of brain respiration, the response is an immediate pulse of reduction in all cytochromes, followed by a tendency to return to the initial levels. Short trains of pulses of electrical field stimulation result in a biphasic change in the level of reduction of cyt a3, an initial slight reduction being followed by a transient of increased oxidation. This response can be abolished by low-sodium bathing solution but not by ouabain. Cytochromes a, b and c show a simple oxidative response to electrical stimulation; the kinetics of this oxidative response are similar to those of the oxidative transient of the cyt a3 response. Pyridine nucleotides, as measured by their fluorescence, respond to electrical stimulation with a transient oxidation which exhibits slower kinetics than the response of the cytochromes. The high resting levels of reduction of cyt a and cyt a3, the reductive response to ouabain and potassium, and the oxidative response of all cytochromes to electrical stimulation suggest a tighter coupling between oxygen utilization and neuronal function than would be expected if mitochondrial redox states simply reflected changes in phosphate acceptor potential resulting from activity of Na+-K+ ATPase.
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PMID:Response of toad brain respiratory chain enzymes to ouabain, elevated potassium, and electrical stimulus. 18 53

The technique of saturation transfer electron spin resonance has been applied to study the rotational diffusion of spin-labeled Ca2+, Mg2+-dependent ATPase molecules in the membranes of sarcoplasmic reticulum vesicles. Comparison of the present data with those for spin-labeled hemoglobin undergoing isotropic rotation leads to a value of 2 X 10(-4) s for the apparent rotational correlation time at 20 degrees C for the membrane-bound protein. Consideration of the anisotropy of the Brownian rotation of the membrane-bound ATPase suggests that the true correlation time for the expected axial rotation may be somewhat smaller than the apparent value. An Arrhenius plot of the rotational motion shows a break, which is interpreted as indicating the occurrence of a conformational change of the ATPase molecule at about 15 degrees C.
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PMID:Saturation transfer electron spin resonance study on the rotational diffusion of calcium- and magnesium-dependent adenosine triphosphatase in sarcoplasmic reticulum membranes. 21 Nov 20

Treatment of Friend erythroleukemia cells with several different chemical agents causes an early decrease in the 86Rb+ influx mediated by Na+/K+ adenosine triphosphatase (ATPase). These agents, which induce Friend cells to differentiate, include dimethylsulfoxide (DMSO), ouabain, hypoxanthine, and actinomycin D. The magnitude of the early decrease in 86Rb+ influx correlates with the proportion of cells in cultures of inducible Friend cell clones which later go on to synthesize hemoglobin. Compounds which do not incude differentiation in these cells, such as xanthine, exogenous hematin, and erythropoietin, do not cause a change in 86Rb+ influx. A change in the intracellular K+ ion concentration does not occur during induction by DMSO because, although there is a decrease in K+ content per cell soon after induction, there is a parallel decrease in cell volume. These results and previous observations from this laboratory are discussed in terms of the posible involvement of the Na+/K+ ATPase in Friend cell differentiation.
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PMID:The program of Friend cell erythroid differentiation: early changes in Na+/K+ ATPase function. 21 40

The fate of vanadate (+5 oxidation state of vanadium) taken up by the red cell was studied using EPR spectroscopy. The appearance of an EPR signal indicated that most of the cytoplasmic vanadate is reduced to the +4 oxidation state with axial symmetry characteristic of vanadyl ions. The signal at 23 degrees C was characteristic of an immobilized system indicating that the vanadyl ions in the cytoplasm are associated with a large molecule. [48V]Vanadium eluted with hemoglobin when the lysate from Na3[48V[O4-treated red cells was passed through a Sephadex G-100 column and rabbit anti-human hemoglobin serum caused a hemoglobin-specific precipitation of 48V when added to the red cell lysate. Both results indicate that hemoglobin is the protein which binds cytoplasmic vanadyl ions. However, neither sodium vanadate nor vanadyl sulfate bound to purified hemoglobin in vitro. Finally, transient kinetics of vanadyl sulfate interaction with the sodium-and potassium-stimulated adenosine triphosphatase showed that the +4 oxidation state of vanadium is less effective than the +5 oxidation state in inhibiting this enzyme. These results indicate that oxidation-reduction reactions in the cytoplasm are capable of relieving vanadate inhibition of cation transport.
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PMID:The fate of cytoplasmic vanadium. Implications on (NA,K)-ATPase inhibition. 21 70

Sealed hemoglobin-free erythrocyte vesicles have been isolated. Imposition of transmembrane cation gradients increases the intensity of Raman scattering in the CH3-stretching region as observed with unsealed ghosts at temperatures greater than 38 degrees C and pH less than 7.0 [Verma, S. P. & Wallach, D. F. H. (1976) Proc. Natl. Acad. Sci. USA 73, 3358--3561]. Modifications in the amide I and amide III frequencies consistent with increased helicity of membrane proteins are observed upon imposition of a cation gradient. Spectrin-free vesicles also demonstrate cation gradient-sensitive intensity changes in the CH3-stretching region. However, no evidence for cation gradient-related protein conformation changes is found with these vesicles. The transmembrane potential of these vesicles has been altered by variations in anion composition and the electrogenic activity of Na+,K+-ATPase. The membrane potential was monitored by cyanine dye fluorescence. Imposition of a membrane potential (negative inside) also increased the intensity of Raman scattering in the CH3-stretching region. These results suggest that a transmembrane potential (negative inside) and/or cation gradient can energize membranes by compression of the apolar region and transfer of protein methyl residues into polar regions.
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PMID:Effect of transmembrane ion gradients on Raman spectra of sealed, hemoglobin-free erythrocyte membrane vesicles. 28 96

A calcium-activated factor (CaAF) has been isolated and partially purified from the post-myofibrillar supernatant fraction of rabbit skeletal muscle. The 200-fold purified CaAF hydrolyzed denatured casein, [3-H]acetyl hemoglobin, and N-ethyl[3-H]maleimide-labeled alpha-actinin. The proteolytic activity has a pH optimum at 6.9 and is dependent on the presence of Ca2+ (optimum concentration, 10 mM). Digestion of isolated myofibrils with CaAF results in removal of Z-lines and in a parallel loss of a 90, 000-dalton protein that has a mobility identical with that of alpha-actinin as determined by polyacrylamide gel electrophoresis. A protein with the properties of alpha-actinin (identical electrophoretic mobility, and ability to accelerate the Mg2+-activated ATPase of reconstituted actomyosin) was isolated from the supernatant of CaAF-treated myofibrils. The release of alpha-actinin from myofibrils by the calcium-activated neutral protease occurs in the absence of detectable change in the electrophoretic profiles of the other myofibrillar proteins, or in the ethylene glycol bis(beta-aminoethyl ether)-N, N' tetraacetic acid (EGTA) sensitivity of Mg2+-activated ATPase. In contrast to the specific removal of Z-lines and of alpha-actinin by CaAF, trypsin treatment of myofibrils results in extensive degradation of myosin heavy chains and of the inhibitory component of troponin (TN-I), and in loss of EGTA sensitivity of myofibrillar ATPase. The degradation of TN-I and loss of EGTA sensitivity occur before the Z-line disappearance.
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PMID:Removal of Z-lines and alpha-actinin from isolated myofibrils by a calcium-activated neutral protease. 80 38

Induction of erythroid differentiation in ouabain-resistant murine erythroleukemia cells by ouabain is reported. Ouabain induction results in the appearance of hemoglobin-containing cells 12-24 hr earlier than induction of the same clone by dimethyl sulfoxide. The levels of globin mRNA after ouabain induction are similar in amount to the globin mRNA levels observed after induction by dimethyl sulfoxide. The concentration of ouabain required to induce hemoglobin synthesis depends upon the K+ ion levels in the culture medium. Lowering the extracellular K+ ion concentration 2-4 fold reduced by 10-40 fold the ouabain concentration necessary for the induction of hemoglobin synthesis. In low K+ medium (1.8 mM), ouabain is an effective inducer of hemoglobin synthesis at a concentration of 0.02 mM. This K+ effect is specific for ouabain induction, since induction by other inducers, such as dimethyl sulfoxide and dimethyl acetamide, does not exhibit this marked sensitivity to the levels of K+ ions in the culture medium. These results suggest that the binding of ouabain to the plasma membrane enzyme, Na/K ATPase, is required for the induction of erythroid differentiation by ouabain. A small but significant proportion of wild-type, ouabain-sensitive cells also can be induced by ouabain, below ouabain concentrations that are toxic to these cells. The observation that the binding of ouabain to the Na/K ATPase induces hemoglobin synthesis suggests that changes in the intracellular concentration of K+ ions may be involved in the control of erythroid differentiation in Friend erythroleukemic cells.
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PMID:Induction by ouabain of hemoglobin synthesis in cultured Friend erythroleukemic cells. 99 Dec 69

To elucidate the mechanism of hyperkalemia in diabetic patients without renal failure, we investigated (Na(+)-K+) adenosine triphosphatase (ATPase) activity in erythrocyte membrane, erythrocyte Na+ and K+ content, and plasma endogenous digitalis-like substance in control subjects (n = 16) and non-insulin-dependent diabetes mellitus (NIDDM) patients (n = 62). NIDDM patients were divided into normokalemic patients (NKDM, n = 48) and hyperkalemic patients (HKDM, n = 14). There was no difference in plasma glucose or hemoglobin A1c (HbA1c) levels, plasma renin activity (PRA), and plasma aldosterone concentrations (PAC) between NKDM and HKDM patients. (Na(+)-K+)ATPase activities in NIDDM patients were significantly reduced compared with those in control subjects (0.336 +/- 0.016 mumol-inorganic phosphate [Pi]/mg protein/h, mean +/- SEM, P less than .05), and (Na(+)-K+)ATPase activities in HKDM patients (0.243 +/- 0.015 mumol Pi/mg protein/h) were significantly reduced compared with those in NKDM patients (0.295 +/- 0.008 mumol Pi/mg protein/h, P less than .01). Plasma K+ content had a significant negative correlation with (Na(+)-K+)ATPase activity in diabetic patients (r = -.365, P less than .01). Erythrocyte Na+ content had a significant negative correlation with (Na(+)-K+)ATPase activity in control subjects (r = -.619, P less than .05). There was no difference in plasma endogenous digitalis-like substance among the three groups. (Na(+)-K+)ATPase activity was not significantly correlated with plasma endogenous digitalis-like substance in control subjects and diabetic patients. These findings suggest that the reduction of (Na(+)-K+)ATPase activity, which was not related to plasma digitalis-like substance, may be partly responsible for hyperkalemia in diabetic patients.
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PMID:Reduction of erythrocyte (Na(+)-K+) ATPase activities in non-insulin-dependent diabetic patients with hyperkalemia. 131 28

Oxidative damage to the membrane in canine erythrocytes with inherited high Na, K-ATPase activity (HK cells) was compared with that in normal canine cells (LK cells). When 30 mM beta-acetylphenylhydrazine (APH) was applied to HK and LK cells, lipid peroxidation and hemoglobin denaturation occurred. Lipid peroxidation determined from malondialdehyde (MDA) formation was significantly lower in HK than in LK cells so far as endogenous glutathione (GSH) concentration was maintained at appropriate levels. With the depletion of GSH, MDA formation was accelerated and difference between HK and LK cells was not significant. Denatured hemoglobin bound to the membrane protein was less in HK than in LK cells. During incubation with APH, osmotic fragility increased markedly in LK cells, while HK cells showed very little change. The amounts of total lipid, total and free cholesterol, glycolipid, phospholipid and fatty acids were essentially the same in both cell types. Fatty acid compositions showed very small differences. The membrane of HK cells thus appear to have greater protection against oxidative damage induced by APH, owing to the presence of excess GSH in HK cells. The capability of HK cells to withstand oxidative damage would not be due to differences in membrane lipid compositions.
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PMID:Oxidative damage to the membrane of canine erythrocytes with inherited high Na, K-ATPase activity. 131 7

We have developed the multiprobe assembly (MPA) by which metabolic, ionic and electrical activities can be monitored from the surface of the brain. In the present study we included optical fibers for the monitoring of intracapillary hemoglobin oxygenation by use of the Erlangen Microlight Guide Spectrophotometer (EMPHO-I) from the surface of the gerbil brain. The newly developed MPA provides simultaneous information about oxygen delivery (oxydeoxy Hb), tissue pO2 level, as well as the intracellular oxygen balance (intramitochondrial redox state). The ionic homeostasis was evaluated by monitoring extracellular K+ and Ca2+ activities reflecting the permeability changes of cation channels as well as the activities of Na+,K(+)-ATPase and other ion linked transport processes. The electrical activities were monitored by a bipolar electrocortical surface probe and DC steady potential. The subjects of the present study were Mongolian gerbils (Meriones unguiculatus) anesthetized and operated according to our routine techniques. After 30 min of recovery from the operation each gerbil was exposed to a short anoxia, graded hypoxia, ischemia as well as spreading depression. The results can be summarized as follows: 1. A clear correlation was recorded between the changes in oxydeoxy Hb spectra, tissue pO2 level and oxidation-reduction state of intramitochondrial NADH under oxygen deficiency situations (hypoxia, ischemia). 2. Blood volume changes under various perturbations monitored by various probes (366 reflectance and EMPHO-I) correlated very well with each other. 3. The degree of inhibition of Na+,K(+)-ATPase induced by oxygen deficiency could be interpreted by changes in extracellular levels of K+ measured by the surface mini-electrode. 4. Brain stimulation induced by spreading depression mechanism led to transient changes in ionic homeostasis and increase in energy requirements. The major HbO2 response was an increase in oxygenation due to the large CBF increase as monitored by the laser Doppler flowmeter. 5. Changes in oxy-deoxy Hb under fast scanning of 500-600 nm during 2-3 seconds of bilateral carotid arterial occlusion provided an indirect index for tissue O2 consumption.
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PMID:Multiparametric evaluation of brain functions in the Mongolian gerbil in vivo. 133 23


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