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Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The portion of Escherichia coli adenosine triphosphatase (ATPase) which is peripheral to the membrane (ECFl) is composed of five separate polypeptides referred to as alpha, beta, gamma, delta, and epsilon. Treating purified ECFl with pyridine precipitated the three larger polypeptides (alpha, beta, and gamma), but the two smaller ones (delta and epsilon), which represent only about 10% of ECFl, remained in solution. After removing the pyridine, both delta and epsilon were active and both were obtained in essentially pure form after chromatography on a single molecular-seive column. epsilon strongly inhibited the ATPase activity of ECFl, indicating that epsilon has a regulatory role in the enzyme. epsilon inhibited ECFl missing delta, indicating that delta is not required for inhibition by epsilon. However, enzyme containing just the alpha and beta subunits, which was prepared by treating ECFl with a protease, was fully active hydrolytically but not at all sensitive to inhibition by epsilon. This result suggests that the gamma polypeptide is required for the inhibition of the ATPase by epsilon. delta restored the capacity of ECFl missing delta to recombine with ECFl-depleted membrane vesicles. The ECFl, which became attached to the vesicles by the added delta, was functional in energy transduction, as evidenced by the coupling of ATP hydrolysis to the transhydrogenase reaction in the vesicles. The rebinding of ECFl missing delta was directly proportional to the amount of delta added until all the ECFl receptors in the membranes were occupied. delta may be a stalk which connects the Fl headpiece to the membrane, since the attachment of ECFl to the membrane exhibited an absolute dependence on delta. Although delta is known to have an apparent molecular weight of about 20,000 by gel electrophoresis in the presence of sodium dodecyl sulfate, the active delta eluted from a molecular-seive column with an apparent molecular weight of about 35,000, suggesting that in the active form delta is a dimer or rather elongated in shape. The active epsilon subunit eluted from the same column with an apparent molecular weight of about 16,000.
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PMID:Purification of membrane attachment and inhibitory subunits of the proton translocating adenosine triphosphatase from Escherichia coli. 13 33

In the normal and randomly reinnervated plantaris muscle of rat staining for succinic dehydrogenase (SDH) activity differentiates three fiber types (A, B and C), staining for myofibrillar adenosine triphosphatase (ATPase) differentiates three fiber types (alpha, beta and alpha beta). Here we present our finding type A corresponds to alpha beta fibers, B to beta or alpha beta, C to alpha or alpha beta. In normal soleus muscle both classifications were found to be compatible and B fibers correspond to beta and C to alpha fibers. An exception is the small percent of alpha beta fibers which correspond to B type. In randomly reinnervated soleus muscle changes in ATPase activity are not followed by changes in SDH staining and B fibers correspond to alpha, beta or alpha beta types.
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PMID:Classification of muscle fiber types based on succinic dehydrogenase and myofibrillar ATPase reactions in normal and randomly reinnervated rat skeletal muscles. 14 Aug 39

Rubratoxin B, an alpha, beta unsaturated lactone containing bisanhydride metabolite of certain toxigenic strains of penicillium molds, significantly inhibited in vitro brain microsomal Na+ - K+ adenosine triphosphatase from swine, mouse, and rat with IC50's of 6.76, 6.67, and 6.80 x 10(-6) M, respectively. Mitochondrial Mg++ oligomycin-sensitive ATPase from mouse liver was also inhibited with an IC50 of 6.30 x 10(-6) M rubratoxin B. Structural modification of the polyfunctional parent compound (rubratoxin B) to rubratoxin A (a gamma lactol replaces one of the anhydride moieties) or formation of the dihydro analogs of rubratoxins A and B (2,3 saturated delta lactone) decreased inhibition to all ATPase systems. The structure-activity relationship relative to ATPase inhibition was rubratoxin B greater than dihydrorubratoxin B greater than rubratoxin A greater than dihydrorubratoxin A. The order of reactivity by these analogs to brain microsomal Na+ -K+ ATPase from 3 mammalian species and to mouse hepatic mitochondrial Mg++ ATPase was similar, indicating no significant species variations. These results suggest that the previously demonstrated in vivo inhibition of adenosine triphosphatase preparations by rubratoxin B was the result of the intact parent compound, because chemical alteration of any one of the functional moieties (either the maleic anhydride ring or conjugated lactone) resulted in significantly decreased inhibition of ATPase activity.
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PMID:Structural modification of polyfunctional rubratoxin B: effects on mammalian adenosine triphosphatase. 21 44

Subunits alpha, beta and gamma of adenosine triphosphatase (H(+)-ATPase) from the thermophilic bacterium PS3 (TF1) have been over-expressed in Escherichia coli. alpha and beta subunits deuterated to the level of 90% were obtained by culturing E. coli in 2H2O medium. Both the subunits and the reconstituted alpha beta gamma complex, TF1, which contain the deuterated components in various combinations, were studied in solution by small-angle neutron scattering. The individual shapes of the subunits and their organization in the alpha beta gamma-TF1 complex were examined using the techniques of selective deuteration and contrast variation. The alpha and beta subunits are well approximated as ellipsoids of revolution having minor semi-axes of 20.4(+/- 0.4) and 20.0(+/- 0.2) A, and major semi-axes of 53.0(+/- 1.4) and 55.8(+/- 0.9) A, respectively. In the TF1 complex, three beta subunits are aligned to form an equilateral triangle, with their major axes tilted by 35 degrees with respect to the 3-fold axis of the complex. The beta-beta distance is about 53 A. Three alpha subunits are similarly arranged, positioned between the beta subunits, and with their direction of tilt opposite to that of the beta subunits. The centers of the alpha and beta subunits lie in the same plane, forming a hexagon. Adjacent subunits overlap in this model, suggesting that they are not simple ellipsoids of revolution.
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PMID:Small-angle neutron scattering from the reconstituted TF1 of H(+)-ATPase from thermophilic bacterium PS3 with deuterated subunits. 214 Apr 19

The purpose of this investigation was to determine which enzyme activities are true canine neutrophil plasma membrane markers. Three enzymes thought to be present on plasma membranes were chosen for study: 5'-nucleotidase, magnesium-dependent adenosine triphosphatase (Mg2+-ATPase), and leucine aminopeptidase. Both 5'-nucleotidase and Mg2+-ATPase were found to be ectoenzymes in the canine neutrophil but additional Mg2+-ATPase activity was located intracellularly. An endogenous inhibitor of 5'-nucleotidase was found in the cytosol of canine neutrophils. The specific 5'-nucleotidase inhibitor, adenosine 5'-[alpha, beta-methylene] diphosphate also inhibited the canine enzyme in intact cells. Leucine aminopeptidase was located solely in the myeloperoxidase-containing granules of the canine neutrophil. Plasma membrane, as identified by the presence of Mg2+-ATPase and 5'-nucleotidase activities, was separated from other cell organelles by Percoll-density gradient centrifugation of a 10 000 X g supernatant of nitrogen cavitated neutrophils.
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PMID:Canine neutrophil plasma membrane markers. 298 65

Imidazo[4,5-b]pyridines, such as AR-L57, AR-L100 and AR-L115 (Vardax), have been of interest as inotropic agents for the management of congestive heart failure. Although it has been presumed that their activities derive from inhibition of phosphodiesterase, it is now apparent that similar structural analogs possess surprisingly diverse pharmacologies and mechanisms of action. AR-L100 increased the contractile state of cat papillary muscles in a concentration-dependent manner; these effects were not blocked by either alpha, beta or H2-receptor antagonists. To determine whether the contractile responses resulted from intracellular cyclic AMP accumulation, the cardiotonic actions of AR-L100 were assessed in the presence of carbachol. Muscarinic receptor stimulation did not alter inotropic responses to AR-L100; in addition, AR-L100 did not potentiate the inotropic actions of isoproterenol. These results imply that cyclic AMP is not involved in the cardiac responses to this agent. AR-L100 inhibited Na+,K+-adenosine triphosphatase activity of either canine kidney or cardiac sarcolemmal vesicles. Inhibition of this enzyme paralleled inotropic responses in vitro; that is, in papillary muscle, the EC50 for contractility was 11.5 microM compared with an IC50 for inhibition of Na+,K+-adenosine triphosphatase of 8 microM. By contrast, the IC50 for inhibition of phosphodiesterase (isozyme III) was 280 microM. AR-L100 also inhibited sodium pump activity in intact cat papillary muscles. Concentrations of 30 and 100 microM AR-L100 resulted in 13 and 45% decreases in ouabain-sensitive 86Rb+ uptake determined at 3 Hz. In anesthetized dogs, AR-L100 increased contractility but did not alter either heart rate or mean arterial blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Molecular basis for the in vitro and in vivo cardiotonic activities of AR-L100. 302 55

The number of sulfhydryl groups in each subunit of the F1 adenosine triphosphatase of Salmonella typhimurium was measured by the method of T. E. Creighton [1980, Nature (London) 284, 487-489]. The alpha, beta, gamma, delta and epsilon subunits of this enzyme contained 4, 1, 2, 2, and 0 sulfhydryl groups per molecule of subunit, respectively.
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PMID:Subunit distribution of the sulfhydryl groups of the F1 adenosine triphosphatase of Salmonella typhimurium. 315 42

The activity of plasma membrane marker enzymes which are involved in purine metabolism (5'-nucleotidase, alkaline 5'-nucleotide phosphodiesterase), in active ion transport (Na-K-Mg-adenosine triphosphatase, ouabain-sensitive Na-K-adenosine triphosphatase), in aminoacid transport (gamma-glutamyltranspeptidase), and in basic physiologic functions (alkaline phosphomonoesterase) were assayed in mononuclear cells isolated from peripheral blood of normal donors and of patients with primary immunodeficiency. Irrespective of the clinical classification of the immunodeficiency, the cells of patients were characterized by significantly diminished 5'-nucleotidase and to a certain extent by lower alkaline phosphomonoesterase activities. Average activity levels of other enzymes were similar in cells of patients and controls, but scattering was more pronounced in the first group. Determination of substrate affinity revealed different kinetic properties of 5'-nucleotidase in cells from patients and normal donors; however, the extent of inhibition by beta-glycerophosphate or alpha, beta-adenosine-methylene diphosphate was comparable for both types of cells. The presence of inhibitory compounds in patients' serum was excluded by mixing experiments. When activities of the various plasma-membrane-associated enzymes were compared with each other, significant correlations emerged in normal lymphocytes. Most of these correlations were absent in cell membranes of immunodeficient patients. The findings indicate that the plasma membrane of lymphocytes from patients with immunodeficiency may be characterized by an altered distribution of enzymatic constituents.
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PMID:Correlations between enzymatic and immunologic properties of human peripheral blood mononuclear cells. I. Ectoenzymes of normal and immunodeficient peripheral blood mononuclear cells. 612 61

The distribution and total number of sulfhydryl groups present in the F1 adenosine triphosphatase of Escherichia coli were used to calculate the stoichiometry of the alpha-delta subunits. Titration with 5,5'-dithiobis (2-nitrobenzoate) gave 19.1 +/- 2.2 sulfhydryl groups/mol ATPase. Labeling with [14C]iodoacetamide and [14C]N-ethylmaleimide showed that 11.9, 3.1, 1.9, and 1.8 sulfhydryl groups per molecule of ATPase were associated with the alpha, beta, gamma, and delta subunits, respectively. The epsilon subunit was not labeled. Application of the method of Creighton [Nature (London) (1980) 284, 487-489] showed that 4, 1, and 2 sulfhydryl groups were present in the alpha, beta, and gamma subunits, respectively. This, together with published data for the delta subunit, allowed a subunit stoichiometry of alpha 3 beta 3 gamma delta to be calculated. The presence of four cysteinyl residues in the alpha subunit, as shown by several different methods, does not agree with the results of DNA sequencing of the ATPase genes [H. Kanazawa, T. Kayano, K. Mabuchi, and M. Futai (1981) Biochem. Biophys. Res. Commun. 103, 604-612; N. J. Gay and J. E. Walker (1981) Nucl. Acids Res. 9, 2187-2194] where three cysteinyl residues/alpha subunit have been found. It is suggested that post-translational modification of the alpha subunit to add a fourth cysteinyl residue might occur.
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PMID:Sulfhydryl groups of the F1 adenosine triphosphatase of Escherichia coli and the stoichiometry of the subunits. 623 Sep 95

An energy-transducing adenosine triphosphatase (ATPase, EC 3.6.1.3) that contains an extra polypeptide (delta) as well as three intrinsic subunits (alpha, beta, gamma) was purified from Micrococcus lysodeikticus membranes. The apparent subunit stoichiometry of this soluble ATPase complex is alpha 3 beta 3 gamma delta. The functional role of the subunits was studied by correlating subunit sensitivity to trypsin and effect of antibodies raised against holo-ATPase and its alpha, beta and gamma subunits with changes in ATPase activity and ATPase rebinding to membranes. A form of the ATPase with the subunit proportions 1.67(alpha):3.00(beta:0.17(gamma) was isolated after trypsin treatment of purified ATPase. This form has more than twice the specific activity of native enzyme. Other forms with less relative proportion of alpha subunits and absence of gamma subunit are not active. Of the antisera to subunits, only anti-(beta-subunit) serum shows a slight inhibitory effect on ATPase activity, but its combination with either anti-(alpha-subunit) or anti-(gamma-subunit) serum increases the effect. The results suggest that beta subunit is required for full ATPase activity, although a minor proportion of alpha and perhaps gamma subunit(s) is also required, probably to impart an active conformation to the protein. The additional polypeptide not hitherto described in Micrococcus lysodeikticus ATPase had a molecular weight of 20 000 and was found to be involved in ATPase binding to membranes. This 20 000-dalton component can be equated with the delta subunit of other energy-transducing ATPases and its association with the (alpha, beta, gamma) M. lysodeikticus ATPase complex appears to be dependent on bivalent cations. The present results do not preclude the possibility that the gamma subunit also plays a role in ATPase binding, in which, however, the major subunits do not seem to play a role.
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PMID:Role of the subunits of the energy-transducing adenosine triphosphatase from Micrococcus lysodeikticus membranes studied by proteolytic digestion and immunological approaches. 644 1


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