Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Treatment with neuraminidase decreased the activity of Na+,K+-activated Mg2+-adenosine triphosphatase in plasma membranes isolated from experimental granulation tissue but not that of 5'-nucleotidase or leucine-beta-naphthylamidase. A temporary lowering of the pH of the plasma membrane suspension to 2-3 inactivated all three enzymes, which remained inactive after the pH had been readjusted to 7.4. Addition of dextran preparations to the membrane suspension decreased the activity of adenosine triphosphatase. Ethanol (0.4%) had a similar effect. These marker enzymes of plasma membranes were not affected by additions of hyaluronate, chondroitin sulfate, protein polysaccharide or soluble collagen. Serotonin stimulated the adenosine triphosphatase activity slightly. About 10-20% of the protein in the plasma membrane preparation was extracted with EDTA. This "fuzzy coat" fraction yielded a distinct gel-electrophoretic protein pattern. Hyaluronidase was not helpful in cleaving this surface layer from the plasma membranes.
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PMID:Properties of plasma membranes from granulation tissue with reference to extracellular matrix. 0 56

Chromaffin granules isolated from bovine adrenal gland were incubated with (3)H-labelled nucleotides and [(14)C]noradrenaline to study the uptake of these substances. [(3)H]ATP, [(3)H]ADP and [(3)H]AMP are taken up by these organelles by the same temperature-dependent mechanism. The apparent K(m) for ATP and ADP is 1.4mm, and for AMP it is 2.9mm. The uptake of ATP has a flat pH optimum, whereas the catecholamine uptake increases with more alkaline pH. Atractyloside and carboxyatractyloside are competitive and specific inhibitors of nucleotide uptake, whereas reserpine inhibits only that for catecholamines. Mg(2+) ions activate uptake of both catecholamine and nucleotides, whereas EDTA and N-ethylmaleimide inhibit these processes. Nucleotide and catecholamine uptakes are inhibited by uncouplers of oxidative phosphorylation and by two ATP analogues. NH(4) (+) ions and nigericin in the presence of KCl inhibit only catecholamine uptake. It is concluded that nucleotide uptake, as proposed previously for catecholamine uptake, depends on an electrochemical proton gradient produced by a proton-translocating adenosine triphosphatase localized in the membrane of chromaffin granules. Furthermore, as suggested by the effect of NH(4) (+) and nigericin, catecholamine uptake apparently depends on the chemical part of this gradient, whereas the results for nucleotide uptake are consistent with its dependence on the electrical component.
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PMID:A characterization of the nucleotide uptake of chromaffin granules of bovine adrenal medulla. 2 25

Three new techniques are described for staining the Langerhans cell in whole mounts of fresh human and guinea pig epidermis. These employ paraphenylenediamine, gold sodium thiomalate and cobalt chloride, respectively, and require appropriate epidermal separation with EDTA, ammonium thiocyanate or sodium bromide. Used in conjunction with a modified adenosine triphosphatase stain, these techniques provide greater capability for observing the Langerhans cell in disease states than can be achieved by any single stain. A combined stain with adenosine triphosphate and gold is also described.
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PMID:New staining techniques for the Langerhans cell. 7 Sep 19

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 properties of a Ca2+ activated adenosine triphosphatase shown to be present in homogenates of purified rat peritoneal mast cells were investigated. The enzyme was activated by Ca2+, Mg2+, and to a lesser extent by Mn2+ and Co2+. Ca2+ alone was necessary for full activity and the further addition of Mg2+ did not have any effect. The chelating agents EGTA (ethanedioxybis(ethylamine)tetra-acetate) and EDTA completely inhibited the reaction. The pH optimum was 7.8. Reduced glutathione, cysteine, dithiothreitol, N-ethylmaleimide, urea, ADP, NaF, increasing ionic strength and Triton X-100 all inhibited the reaction. On subcellular fractionation of mast-cell homogenates by density-gradient centrifugation, the distribution of Ca2+ activated adenosine triphosphatase resembled that of 5'-nucleotidase, but differed from that of the other markers used, suggesting localization in the plasma membrane. Further experiments indicated that the enzyme is present on the external surface of the plasma membrane.
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PMID:Characterization of calcium-ion-activated adenosine triphosphatase in the plasma membrane of rat mast cells. 13 82

Adenosine triphosphate (ATP) hydrolysis catalyzed by the plasma membrane (Na+,K+)ATPase isolated from several sources was inhibited by Mg+, provided that K+ and ATP were also present. Phosphorylation of the adenosine triphosphatase (ATPase) by ATP and by inorganic phosphate was also inhibited, as was p-nitrophenyl phosphatase activity. (Ethylenedinitrilo)tetraacetic acid (EDTA) and catecholamines protected from and reversed the inhibition of ATP hydrolysis by Mg2+, K+ and ATP. EDTA was protected by chelation of Mg2+ but catecholamines acted by some other mechanism. The specificities of various nucleotides as inhibitors (in conjunction with Mg2+ and K+) and as substrates for the (Na+, K+) ATPase were strikingly different. ATP, ADP, beta,gamma-CH2-ATP and alpha,beta-CH2-ADP were active as inhibitors, whereas inosine, cytidine, uridine, and guanosine triphosphates (ITP, CTP, UTP, and GTP) and adenosine monophosphate (AMP) were not. On the other hand, ATP and CTP were substrates and beta,gamma-NH-ATP was a competitive inhibitor of ATP hydrolysis, but not an inhibitor in conjunction with Mg2+ and K+. The Ca2+-ATPase from sarcoplasmic reticulum and F1, the Mg2+-ATPase from the inner mitochondrial membrane, were also inhibited by Mg2+. Catecholamines reversed inhibition of the Ca2+-ATPase, but not that of F1.
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PMID:Reversible inhibition of (Na+, K+) ATPase by Mg2+, adenosine triphosphate, and K+. 13 42

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.
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PMID:Characteristics of sarcoplasmic reticulum from slowly glycolysing and from rapidly glycolysing pig skeletal muscle post mortem. 14 57

The histochemical activity of adenosine triphosphatase (ATPase) was studied at light and electron microscopic levels in larval tail musculature of Rana catesbeiana and Rana ornativentris during late metamorphic stages. The presence of low, moderate or dark reaction of K2-EDTA-preincubated Ca++-ATPase was correlated with the variable degree of degeneration of white fibres even at the late stage of tail resorption. The reasons for an increase in this ATPase activity in degenerating white muscle fibres are discussed. Irrespective of the degree of degeneration, all red fibres showed high ATPase reaction. During myocytolysis, it is shown that the SR vesicles accumulate electron dense amorphous material. The degree of myofibrillar disintegration correlated with decrease in ultrastructural reaction product for Mg++-ATPase. Although grouped atrophy of muscle fibres (as seen in Xenopus laevis, den Hartog Jager et al., 1973, 1975) was absent in musculature of resorptive tails, ultrastructural characteristics including proliferation of SR and dilation of its vesicles represent alteration of the normal neural influence on the skeletal muscle fibres.
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PMID:Light and electron microscopic investigation of ATPase activity in musculature during anuran tail resorption. 15 41

1. The naturally occurring ATPase (adenosine triphosphatase)-inhibitor protein, from bovine heart mitochondria, was obtained as a single pure protein. It was not identical with any of the five subunits (alpha-epsilon) of the isolated ATPase, and appeared to be a single polypeptide chain. 2. The inhibitor combined with the ATPase in a 1:1 molar ratio, producing a completely inhibited ATPase molecule. The affinity of the ATPase for its inhibitor is high; the K(d) is of the order of 10(-8)m. 3. The enthalpy of the ATPase-inhibitor complex-formation is positive, the value of K(d) decreasing as the temperature is raised. This suggests that the forces involved are largely hydrophobic in nature. 4. Hydrolysis of a nucleoside triphosphate promoted formation of the ATPase-inhibitor complex, although the equilibrium position was almost unaffected by the rate of hydrolysis. At low salt concentration, less than 200 turnovers of the ATPase suffice for the ATPase to combine with the inhibitor protein. At higher salt concentrations, a larger number of turnovers is required. It is suggested that the inhibitor binds to a form of the ATPase that is produced transiently during hydrolysis. 5. In the presence of 75mm-K(2)SO(4), the rates of association and dissociation are slow enough to allow their kinetics to be studied. Association is first-order in inhibitor concentration, but fractional order in ATPase concentration. Dissociation is first-order in ATPase-inhibitor complex concentration. The temperature coefficients of the ;on' and ;off' processes were also measured. 6. A simple kinetic model for the ATPase-inhibitor interaction is proposed that can be extended to take into account release of inhibitor protein under energized conditions on the membrane. 7. The isolated ATPase is inhibited by preincubation with Mg(2+), reversible by subsequent addition of EDTA, and by ADP, reversible by subsequent addition of ATP. These effects are not found on the membrane-bound ATPase. The mechanism of these effects is discussed.
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PMID:A thermodynamic analysis of the interaction between the mitochondrial coupling adenosine triphosphatase and its naturally occurring inhibitor protein. 15 88

The histochemical activities of myofibrillar adenosine triphosphatase (ATPase), succinic dehydrogenase (SDH) and alpha glycerophosphate dehydrogenase (alpha-GPD) were studied in intrafusal muscle fibres of rat fast and slow muscles. The ATPase reaction was carried out after the three standard acid preincubations. The cold K2-EDTA preincubated ATPase reaction product was similar to that seen following the regular or alkali-preincubated ATPase reaction, except that the intermediate bag fibres exhibited much higher activity after cold K2-EDTA preincubation. Following either acetic acid solution or cold and room temperature K2-EDTA-preincubation, followed by the ATPase reaction, chain fibres of the fast muscles vastus lateralis and extensor digitorum longus exhibited a very low amount of reaction product as compared with those of the slow soleus. Veronal acetate and K2-EDTA preincubations (and equally preincubation in acetic acid solution) resulted in acid stable ATPase activity along the entire length of the typical bag fibres but only in the polar regions of the intermediate bag fibres. On the basis of differing alpha-GPD reaction, two sub populations of nuclear chain fibres were discovered in one spindle. It is a matter of conjecture, to what extent the histochemical differences of intrafusal fibres from fast and slow muscles reflects functional distinctions in the response to stretch of muscle spindles from fast and slow muscles.
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PMID:A histoenzymatic study of rat intrafusal muscle fibres. 15 74


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