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)

The content of calcium bound to the erythrocyte membrane and the effect of intracellular calcium concentration on the activity of Na+, K+-ATPase in the reconstituted erythrocytes were studied in 20 patients with essential hypertension and in 20 individuals with normal pressure. In incubation of the erythrocytes in a solution containing EDTA much more calcium is removed from the outer surface of their membrane in patients with essential hypertension than in the control group (60 +/- 5 mEq/l and 41 +/- 3 mEq/l, respectively). When the intracellular calcium concentration varies from 0 to 500 mumol/l, which corresponds to a rise in the free calcium (Ca2f+-3) concentration to 41 mumol/l, a difference in the changes of Na+, K+-ATPase activity of the reconstituted erythrocytes is noted. When intracellular calcium concentration is 50 mumol/l (Ca2f+-3 mumol/l), ATP-ase activity in patients with essential hypertension is 21% less than that in individuals with normal pressure (P less than 0.005). The authors explain the difference in the kinetics of Na+, K+-ATPase changes by the different degree of calcium depletion of the inner surface of the erythrocyte membrane in relatively low Ca2f+ values in the internal medium. The data obtained are evidence of the altered calcium-binding capacity of the erythrocyte membrane, which may cause the increased permeability of the erythrocyte membrane to sodium and potassium ions in patients with essential hypertension, which the authors had revealed earlier. The authors consider the revealed changes to be a fragment of a more extensive membrane defect which may be the principal cause of activation of the servomechanisms which maintain arterial pressure.
Kardiologiia 1977 Sep
PMID:[Role of membrane-bound calcium in the changes of ion permeability and Na+, 5+ and ATPase activity of the erythrocytes in hypertension]. 14 18

The extranuclear mitochondrial oligomycin-resistant mutation of Aspergillus nidulans, (oliA1), was transferred asexually into four nuclear oligomycin-resistant strains of different phenotypes. In all four cases, the possession of the nuclear plus extranuclear mutation led to an increase in the in vivo level of oligomycin resistance. In two cases, the altered cytochrome spectrum and impaired growth ability determined by (oliA1) were suppressed by the nuclear mutations. In the third case, the in vitro oligomycin resistance of the double mutant ATPase was dramatically increased above that of either of the component single mutant strains, indicating a synergystic interaction between the nuclear and extranuclear gene products. In the fourth case, the double mutant became cold-sensitive. A new extranuclear mitochondrial oligomycin-resistant mutation (oliB332) is described. This mutant is phenotypically similar to, though not identical with, (oliA1) but is separable by recombination. A range of nuclear oligomycin-resistant mutants have been mapped. Despite presenting five distinctly different phenotypes, they all map at the same locus.
Mol Gen Genet 1977 Sep 09
PMID:Nuclear-extranuclear interactions affecting oligomycin resistance in Aspergillus nidulans. 14 64

The postjunctional membrane of mouse diaphragm fibres was hyperpolarized by 1-2 mV during local curarization of the end-plate zone in the presence of anticholinesterase. In a solution containing 5 mM K+, the mean hyperpolarization was 1.0+/-0.35 mV. Hyperpolarization was 1.46+/-0.30 mV when the activity of the Na-K pump was blocked by 2 x 10(-5) M ouabain and 1.82+/-0.43 mV when it was blocked by bathing the muscle in a K+-free medium. Reactivation of membrane ATP-ase by addition of potassium after a period in K+-free medium reduced the hyperpolarization to zero, when measurements were made 10-20 min after the readdition. It is concluded that spontaneous non-quantal leakage of acetylcholine occurs at the mouse neuromuscular junction, as it does in the frog (2). Conditions which block the Na+-k+-dependent ATPase increased the leakage whereas potentiation of the pump activity decreased it.
Pflugers Arch 1977 Sep 16
PMID:Non-quantal release of transmitter at mouse neuromuscular junction and its dependence on the activity of Na+-K+ ATP-ase. 14 99

Human erythrocytes from healthy male donors were fractionated with respect to in vivo age by simple centrifugation in order to characterize changes in the functional integrity of the membrane during the life-span of the cell. The three enzymes, Na/K-ATPase, glyceraldehyde-3-phosphate dehydrogenase and NADH-ferricyanide reductase, were found not to change with age, but significant age-dependent decreases were observed in the cases of acetylcholinesterase, phosphoglycerate kinase, purine nucleoside phosphorylase, adenylate kinase, Mg-ATPase and alkaline phosphatase. The possibility that these changes were attributable to mechanisms other than age-related inactivation, such as reticulocyte contamination, differential resealing and crypticity, was investigated. Only the decrease in acetylcholinesterase could be explained wholly in terms of reticulocyte contamination. A decrease in membrane integrity on ageing was observed, which accounted for approximately half the change in alkaline phosphatase and may have contributed to the other enzyme activity changes. This membrane integrity effect masked a real decrease in the highly cryptic NADH-ferricyanide reductase, this decrease being apparent only after total disaggregation of the membrane with nonionic surfactant.
Br J Haematol 1977 Sep
PMID:Changes in the activities of some membrane-associated enzymes during in vivo ageing of the normal human erythrocyte. 14 40

The composition and function of fragmented sarcoplasmic reticulum from pig skeletal muscle was examined in the period immediately post mortem. Muscle was defined as being either slowly glycolysing or rapidly glycolysing on the basis of colour, pH and concentrations of glycogen and lactate. The microsomal fraction was separated on a discontinuous gradient of 35, 40 and 45% (w/v) sucrose into heavy and intermediate fractions which sedimented to the interfaces, and a light fraction which remained on the surface of the 35%-sucrose layer. The sarcoplasmic reticulum from rapidly glycolysing muscle had a lower buoyant density than had that from slowly glycolysing muscle. This was reflected in the consistent lack of material in the heavy fraction and a greater proportion in the light fraction. The latter material had significantly lower ratios (w/w) of protein to phospholipid (2.3:1 versus 3.8:1) and of protein to cholesterol (10.4:1 versus 15.6:1). There were no gross differences in phospholipid content or in fatty acid composition of individual phospholipid classes in the membranes from the two types of muscle. Analysis of membrane proteins by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis showed that ATPase (adenosine triphosphatase) was a major component of each fraction and that its contribution to the total protein content of the membrane was greater in rapidly glycolysing muscle, suggesting a loss of non-ATPase proteins. The two fractions of sarcoplasmic reticulum prepared from rapidly glycolysing muscle had approximately one-third the normal activities of Ca(2+) binding and Ca(2+) uptake in the presence of ATP and one-half the passive Ca(2+)-binding capacity in the absence of ATP of the fractions from slowly glycolysing muscle. However, the (Ca(2+)+Mg(2+))-stimulated ATPase activities were similar. Efflux from actively loaded vesicles, after the addition of EDTA, consisted of a rapid and a slow phase. Vesicles from rapidly glycolysing muscle lost 60% of associated Ca(2+) (approx. 0.10mumol of Ca(2+)/mg of protein) during the rapid phase, compared with 30% (approx. 0.17mumol of Ca(2+)/mg of protein) in those from slowly glycolysing muscle. The efflux rate during the slower phase was comparable in both types of vesicles. Analysis of the temperature-dependence of (Ca(2+)+Mg(2+))-stimulated ATPase activity revealed that a high-activation-energy process operating in the temperature range 31-45 degrees C in the intermediate and light fractions from slowly glycolysing muscle was not apparent in vesicles from rapidly glycolysing muscle. Conditions that result in the prolonged activation of glycogenolysis in pig muscle post mortem primarily affect the protein components of the sarcoplasmic-reticular membrane, giving rise to a loss of loosely associated proteins. The function of the membranes observed under these conditions does not appear to be due to enhanced permeability of the membrane to Ca(2+) and may be the result of a defect in the transport of Ca(2+) into the vesicles.
Biochem J 1977 Sep 15
PMID:Characteristics of sarcoplasmic reticulum from slowly glycolysing and from rapidly glycolysing pig skeletal muscle post mortem. 14 57

1. The fatty acid composition of the ole-1 and ole-1 petite mutants of Saccharomyces cerevisiae was manipulated by growing the organism in the presence of defined supplements of Tween 80 or by allowing cells that had first been grown in the presence of Tween 80 to deplete their unsaturated fatty acids by sequent growth in the absence of Tween 80. 2. The transition temperature of Arrhenius plots of mitochondrial ATPase (adenosine triphosphatase) increases as the unsaturated fatty acid content is lowered. 3. Cells require larger amounts of unsaturated fatty acids to grow on ethanol at lower temperatures. 4. Cells that stop growing owing to unsaturated fatty acid depletion at low temperatures are induced to grow further by raising the temperature and this results in a further depletion of unsaturated acids. This is due to a higher rate, but not a greater efficiency, of mitochondrial ATP synthesis. 5. Arrhenius plots of the passive permeability of mitochondria to protons between 4 and 37 degrees C are linear. The rate and the Arrhenius activation energy of proton entry increase greatly as the unsaturated fatty acid content is lowered. 6. Unsaturated fatty acid depletion has the same effects on the proton permeability of ole-1 petite mitochondria, indicating that the mitochondrially synthesized subunits of the ATPase are not involved in the enhanced rates of proton entry. 7. The adenylate energy charge of depleted ole-1 cells is greatly decreased by growth on ethanol medium. 8. The adenylate energy charge of isolated mitochondria is also lowered by unsaturated fatty acid depletion. 9. The results confirm that unsaturated fatty acid depletion uncouples oxidative phosphorylation in yeast both in vivo and in vitro, and is a consequence of changes in the lipid part of the membrane.
Biochem J 1977 Sep 15
PMID:The effects of unsaturated fatty acid depletion on the proton permeability and energetic functions of yeast mitochondria. 14 59

1. The synthesis of dibutylchloromethyltin chloride, a new covalent inhibitor of the mitochondrial ATP synthase [oligomycin-sensitive ATPase (adenosine triphosphatase)] complex is described, together with a method for preparing dibutylchloro[(3)H]methyltin chloride. 2. Studies with the yeast mitochondrial oligomycin-sensitive ATPase complex show that dibutylchloromethyltin chloride inhibits both the membrane-bound enzyme and also the purified Triton X-100-dispersed preparation. 3. F(1)-ATPase is not inhibited even at 500nmol of dibutylchloromethyltin chloride/mg of protein, and the general inhibitory properties are similar to those of triethyltin, oligomycin and dicyclohexylcarbodi-imide, known energy-transfer inhibitors of oxidative phosphorylation. 4. Binding studies with yeast submitochondrial particles show that dibutylchloromethyltin chloride antagonizes the binding of triethyl[(113)Sn]tin, indicating that there is an interaction between the two inhibitor-binding sites. 5. Unlike triethyltin, inhibition by dibutylchloromethyltin chloride is due to a covalent interaction which titrates a component of the inner mitochondrial membrane present at a concentration of 8-9nmol/mg of protein. 6. All of the labelled component can be extracted with chloroform/methanol (2:1, v/v), and sodium dodecyl sulphate/polyacrylamide-gel electrophoresis of the chloroform/methanol extract indicates that the labelled component has an apparent mol.wt. of 6000-8000. However, t.l.c. reveals the presence of only one labelled component which is lipophilic and non-protein and is distinct from the free inhibitor, mitochondrial phospholipids and the dicyclohexylcarbodi-imide-binding protein (subunit 9). 7. Inhibition of mitochondrial ATPase and oxidative phosphorylation is correlated with specific interaction with a non-protein lipophilic component of the mitochondrial inner membrane which is proposed to be a co-factor or intermediate of oxidative phosphorylation.
Biochem J 1977 Sep 15
PMID:Dibutylchloromethyltin chloride, a covalent inhibitor of the adenosine triphosphate synthase complex. 14 60

The mitochondrial F1-ATPase is irreversibly inactivated by the adenine nucleotide analogue, p-fluorosulfonylbenzoyl-5'-adenosine. This inactivation is partly prevented by the presence of bound adenine nucleotides. Inactivations of the ATPase with p-fluorosulfonyl[14C]benzoyl-5'-adenosine were most efficiently accomplished with the nucleotide-free enzyme at pH 7.0, in a buffer containing 20% glycerol. Under these conditions, 4.2 g atoms of 14C are incorporated per 350,000 g of enzyme when the ATPase is inactivated by 90% by its reaction with 2 mM p-fluorosulfonyl[14C]benzoyl-5'-adenosine. Isolation of the component polypeptide chains of the labeled ATPase showed that all of the radioactivity was associated with the two largest subunits. The isolated alpha subunit contained 0.45 g atom of 14C/mol and the isolated beta subunit contained 0.88 g atom of 14C/mol. Hence, the inactivation can be correlated with the incorporation of 14C into the beta subunit. This suggests that the hydrolytic site of the enzyme resides on this subunit. The majority of the radioactivity in a tryptic digest of labeled beta subunit is contained ina tryptic peptide that has the following amino acid sequence: Ile-Met-Asp-Pro-Asn-Ile-Val-Gly-Ser-Glu-His-Tyr-Asp-Val-Ala-Arg, where Tyr is the radioactive derivative of the tyrosine residue that was sulfonylated during the inactivation.
J Biol Chem 1978 Sep 10
PMID:Identification of a tyrosine residue at a nucleotide binding site in the beta subunit of the mitochondrial ATPase with p-fluorosulfonyl[14C]-benzoyl-5'-adenosine. 15 Apr 16

Acanthamoeba myosin IB is a single-headed enzyme containing one heavy chain of 125,000 daltons, one light chain of 27,000 daltons, and one light chain of 14,000 daltons. The 125,000- and 27,000-dalton polypeptides are consistently found in a molar ratio of 1:1. The content of the 14,000-dalton peptide is usually only 0.1 to 0.2, and always less than 0.5, relative to the other two chains and might be a contaminant or a degradation product of one of the other chains. The specific activities of the Ca2+-ATPase, (K+, EDTA)-ATPase, and (after phosphorylation of its heavy chain by a specific kinase) actin-activated Mg2+-ATPase of Acanthamoeba myosin IB are similar to those of rabbit skeletal muscle myosin. After treatment of the enzyme with 2 M LiCl, the 125,000-dalton heavy chain of Acanthamoeba myosin Ib can be obtained, by chromatography on Sephadex G-200, essentially free of the 14,000-dalton peptide and more than 90% free of the 27,000-dalton peptide. This isolated heavy chain has the same specific ATPase activities as the original enzyme. Therefore, the heavy chain of Acanthamoeba myosin IB contains the ATPase catalytic site, the actin-binding site, and the phosphorylation site and is fully active enzymatically in the absence of light chains.
J Biol Chem 1978 Sep 25
PMID:The isolated heavy chain of an Acanthamoeba myosin contains full enzymatic activity. 15 Apr 18

A study of RBC membrane functions was performed in four patients suffering from familial hypokalemic periodic paralysis who had permanent muscular weakness. Electrophoretograms of membrane proteins, cell deformability, calcium-promoted potassium efflux, calcium-ATPase activity, and endogeneous phosphorylation of membrane proteins were all within the normal range. These results are compared with similar studies performed in myotonic and Duchenne-type dystrophies, in which abnormalities in the RBC membrane have been described. The results do not support the theory of RBC involvement in hypokalemic periodic paralysis. However, this does not imply that the muscle cell membrane is not involved in the underlying pathological processes in this disorder.
Arch Neurol 1978 Sep
PMID:Erythrocyte membrane studies in familial hypokalemic periodic paralysis. 15 Aug 37


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