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)

An effect of hypoxic hypoxia on the total, Mg2+-dependent and Na-K-dependent ATPase activities was studied in rat brain and erythrocytes. In brain tissue under effect of 15 min hypoxia a distinct decrease in all the ATPase activities was observed; the activity of Na-K-dependent ATPase decreased especially distinctly (by 32% of the initial level). Within 90 min of hypoxia the enzymatic activity was partially restored but did not reach the initial level. In erythrocytes 15 min hypoxia was also accompanied by a significant decrease in Na-K-dependent ATPase activity (30.5% of the initial level). But within 90 min the enzymatic activity was distinctly increased (up to 196.4%). Mg2+-dependent ATP-ase was more resistant to oxygen deficiency, Variations in the enzymatic activity were less distinct, although they showed the same pattern as those of the Na-K-dependent ATPase.
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PMID:[Changes in the ATPase activity of the brain and erythrocytes in hypoxia]. 12 82

1. Acetylation of human erythrocytes by N-acetylimidazole alters the structure of stroma prepared from these cells and the degree of alteration appears to be dependent upon the level of the initial treatment. These changes do not occur when stroma are acetylated. 2. Deacetylation by hydroxylamine or mild alkaline treatment causes a complete recovery of the (Na+ plus K+)-dependent and the Ca2+ -stimulated ATPase activities and indicates that the inhibition is due to the acetylation of a tyrosyl residue. There is only partial recovery of the Mg2+ -dependent ATPase after deacetylation. 3. ATP or Mg-ATP completely protect the (Na+ plus K+)-dependent ATPase, but not the Ca2+ -stimulated system. 4. The results indicate that the (Na+ plus K+)-dependent and the Ca2+ -stimulated ATPase activities have separate substrate binding sites and most likely are separate enzyme systems. 5. Acetylation of human erythrocytes has no effect on D-glucose transport.
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PMID:Effects of N-acetylimidazole on human erythrocyte ATPase activity. Evidence for a tyrosyl residue at the ATP binding site of the (Na+ plus K+)-dependent ATPase. 12 69

The requirement of actual splitting of ATP for endocytosis in erythrocyte ghosts has been confirmed by use of the ATP analog, 5'-adenylylimidodiphosphate, (AMP-P(NH)P). This compound, in which the oxygen connecting the beta and gamma phosphorus atoms was replaced by an NH group, did not cause endocytosis nor was it a substrate for ATPase activity. AMP-P(NH)P was a competitive inhibitor both for the endocytosis and the Mg2+-ATPase activities. The K1 of AMP-P(NH)P for Mg2+ ATPase activity was 2.0 - 10-4 M and, while the Km of ATP for this activity was also 2.0 - 10-4 M indicating nearly identical affinities of ATP and AMP-P(NH)P for the active site. ADP, or ADP plus orthophosphate, did not cause endocytosis, showing that endocytosis was not due to binding of the products of ATP hydrolysis. Sodium or potassium ion or ouabain had no effect on endocytosis, which eliminated the possibility of involvement of the Na+, K+ ATPase in the endocytosis process. Calcium could not be substituted for magnesium; rather it inhibited endocytosis at the concentration of 1 - 10-3 M. EGTA relieved the inhibitory effect of Ca, which indicated that the binding of calcium to the membrane was reversible. These experimental results reaffirm the conclusion that ATP must be split to engender endocytosis under these conditions. Some characteristic parameters of the hemoglobin-free porcine erythrocyte ghosts were studied in order to characterize the system more adequately.
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PMID:Energy-dependent endocytosis in erythrocyte ghosts. IV. Effects of Ca2+, Na+ +K+, and 5'-adenylylimidodiphosphate. 12 70

A myosin was isolated from the clonal rat glial cell strain C-6 and compared with rat skeletal muscle myosin. After cell extracts were subjected to gel filtration chromatography in the presence of KI and magnesium pyrophosphate the C-6 myosin was rapidly purified by a procedure similar to that used for skeletal muscle myosin. The C-6 myosin resembles muscle myosin both physically and enzymatically. It contains heavy chains of 200,000 daltons and two classes of light chains of 17,000 and 19,000 daltons in approximately equal molar ratios. This myosin forms bipolar thick filaments in 0.1 M KCl and binds reversibly to skeletal muscle F-actin, the binding being inhibited by MgATP. Skeletal muscle F-actin stimulates the C-6 myosin adenosine triphosphatase 2- to 3-fold in the presence of KCl and Mg2+. The action activation of muscle myosin ATPase at low ionic strength is 10-fold greater than that of C-6 myosin. Ca2+ and EDTA stimulated the ATPase activities of both enzymes. When assayed in the presence of 0.6 M KCl and 1 mM EDTA the skeletal muscle myocin ATPase demonstrates substrate saturation while the C-6 myosin enzyme activity is stimulated by ATP concentrations above 2.5 mM.
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PMID:Purification and characterization of myosin from the clonal rat glial cell strain C-6. 12 31

The Mg2+ -dependent ATPase (EC 3.6.I.3) of Proteus L-form membrane has been solubilized according to various procedures (Tris - HCL shock-wash with or without MG2+, EDTA, Triton X-100). The best results were obtained by the same 33mM Tris-HCL (pH 7.5) shock-wash without MG2+ used for ATPase of protoplasts from Streptococcus faecalis. The solubilized enzyme after 105 000 times g centrifugation was purified on acrylamide/agarose. The molecular weight was established to be 360 000 by gel filtration and by sedimentation coefficient (12.5 S). Polyacrylamide disc-gel electrophoresis in sodium dodecylsulphate revealed two classes or subunit of mol. wt. 64 000 (alpha) and 58 000 (beta), associated in ratio 1:1. We propose a formula alpha-3beta-3 for the native ATPase of Proteus L-forms. Structural similarities to ATPase of various origins are discussed.
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PMID:Membrane ATPase of Proteus L-forms. Solubilization and molecular properties. 12 72

The ionic influence and ouabain sensitivity of lymphocyte mg-2+-atpase and Mg-2+-(Na+ +K+)-activated ATPase were studied in intact cells, microsomal fraction and isolated plasma membranes. The active site of 5'-nucleotidase and Mg2+-ATPase seemed to be localized on the external side of the plasma membrane whereas the ATP binding site of (Na+ +K+)-ATPase was located inside the membrane. Concanavalin A induced an early stimulation of Mg2+-APTase and (Na+ +K+)-ATPase both on intact cells and purified plasma membranes. In contrast, 5'-nucleotidase activity was not affected by the mitogen. Although the thymocyte Mg2+-ATPase activity was 3-5 times lower than in spleen lymphocytes, it was much more stimulated in the former cells (about 40 versus 20%). (Na+ +K+)-ATPase activity was undectectable in thymocytes. However, in spleen lymphocytes (Na+ +K+)-ATPase activity can be detected and was 30% increased by concanavalin A. Several aspects of this enzymic stimulation had also characteristic features of blast transformation induced by concanavalin A, suggesting a possible role of these enzymes, especially Mg2+-ATPase, in lymphocyte stimulation.
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PMID:Effect of concanavalin A on membrane-bound enzymes from mouse lymphocytes. 12 86

Biochemical effects of 3MI on cellular membranes were investigated. This study was conducted to examine the effects of 3MI on the hemolysis of erythrocytes, the transport of 22Na+ in resealed erythrocyte ghosts, and on the ATPase activities of erythrocyte membranes. The percent of hemolysis as a function of 3MI incubation time was sigmoidal. Seventy-five percent of the hemoglobin was released with the second 2 hr of incubation during which the concentration of 3MI in the cells reached a plateau of 2500 mug/ml of packed RBC. The effect of 3MI at a subhemolytic concentration on passive and active 22Na+ transport were not significant. The total and Mg2+-dependent ATPase activities in the membranes were significantly increased after 1 hr of incubation with 3MI at concentrations of 100, 200, 300, 400 and 500 mug/ml (P less than or equal to 0/ml (P smaller than or equal to 0.02).
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PMID:The effects of 3-methylindole on hemolysis, transport of Na+, and ATPase activities of bovine erythrocytes. 12 60

The cellular membrane function expressed as ATPase activity and active cellular K+ changes during in vitro incubation has been studied in two siblings with Bartter's syndrome. The K+ content of skeletal muscle was 20% lower than for controls, and the active potassium transport ability of single skeletal muscle cells was also lower than that of controls. The total ATPase activity of red cell membranes was higher, but the ratio of Na+-K+-activated to Mg2+-activated ATPases was lower than for control patients. The results favour the hypothesis that a primary defect causing the Bartter's syndrome could be an inherited generalized membrane dysfunction in the handling of cations.
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PMID:Cellular potassium transport and ATPase activity in Bartter's syndrome. 12 92

A Mg2+- and Ca2+-stimulated adenosine triphosphatase (ATPase) at the outer surface of intact Ehrlich ascites tumor cells is described. A surface-bound adenosine triphosphate (ATP)-splitting activity at a lower rate was also demonstrated in the absence of Ca2+ but with Mg2+, Na+, and K+ present in the isotonic medium. Hence, when part of the Mg2+ was exchanged for Ca2+, a marked increase of the ATP-splitting activity was observed. The stimulatory effect of Ca2+ was seen only if both Na+ and K+ were present in the isotonic incubation medium. Thus, the enzyme activity was Mg2+- and Ca2+-dependent. Ca2+, together with the monovalent cations was inhibitory compared with Mg2+ under similar conditions. The apparent Km for ATP for the Mg2+-stimulated ATPase is 0.05 mM, while that of the Mg2+- and Ca2+-stimulated enzyme is 0.10 mM. The Vmax of the former is 0.8 mu-mole per 100 mg Schneider protein per 30 sec compared with 1.92 mu-moles per 100 mg Schneider protein per 30 sec for the latter. The calculated Km for the Mg2+- and Ca2+-stimulated ATPase after subtraction of the Mg2+-stimulated part is 0.22 mM. Ethacrynic acid and N-ethylmaleimide both inhibited the Mg2+- and Ca2+-stimulated ATPase by about 10 percent, while the ouabain inhibition was 15 percent. Cytochalasin B did not influence the enzyme activity, whereas La3+ had a slight stimulatory effect.
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PMID:A Mg2+- and Ca2+-stimulated adenosine triphosphatase at the outer surface of Ehrlich ascites tumor cells. 12 5

The activation of ATP reversible Pi exchange, normally associated with a Ca2+ concentration gradient in sarcoplasmic reticulum vesicles, can be obtained in "leaky" vesicles in 4-10 mM CaCl2. In the micromolar range, Ag+ activates the ATP reversible Pi exchange two- to fourfold. Similar concentrations of Ag+ promote a parallel inhibition of Ca2+- activated ATP hydrolysis and Ca2+ uptake in intact vesicles. Maximal inhibition of these activities by Ag+ leaves the Mg2+-dependent ATPase unaffected. No net synthesis of ATP was demonstrated in leaky vesicles. The effects of Ag+ depends on the protein concentration and persist after removal of Ag+ from the medium. Membrane phosphorylation from Pi or from ATP is respectively activated or inhibited by Ag+ in reciprocal fashion.
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PMID:ATP reversible Pi exchange and membrane phosphorylation in sarcoplasmic reticulum vesicles: activation by silver in the absence of a Ca2+ concentration gradient. 12 1


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