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

Thermoacidophilic archaebacteria have gained much interest because of their phylogenetic distance to eubacteria and eukaryotes and also because of their unique living conditions. Investigation of the energy-converting system therefore offers a key for understanding the evolutionary position and environmental adaptation of these unusual bacteria. A plasma-membrane-associated adenosine triphosphatase with specific activities of 0.3-0.6 mumol min-1 (mg protein)-1 has been detected in the thermoacidophilic archaebacterium Sulfolobus acidocaldarius (DSM 639). The enzyme exhibits two optima at pH 5.5 and 8.0, sulfite activation leads to only one optimum at pH 6.25. In the presence of the divalent cations Mg2+ or Mn2+ it hydrolyzes ATP with highest reactivity and also other purine and pyrimidine nucleotides, but not ADP and pyrophosphate. A specific stimulation by monovalent cations is not observed. The ATPase activity is not inhibited by N,N'-dicyclohexylcarbodiimide, azide or vanadate, but it is by the vascular ATPase inhibitor nitrate with an [I]50 of 8 mM. Linear Arrhenius plots up to 75 degrees C reflect pronounced adaptation to the hot environment of the archaebacterium. The solubilized ATPase as localized by activity staining in non-denaturating gels and further analyzed by sodium dodecyl sulfate electrophoresis is composed of two major polypeptides of 65 and 51 kDa reminiscent of the alpha and beta subunits of eubacterial and eukaryotic F0F1-ATPases. The ATPase is suggested as a probable candidate for a reversibly acting ATP synthase responsible for oxidative phosphorylation found in Sulfolobus acidocaldarius.
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PMID:A plasma-membrane associated ATPase from the thermoacidophilic archaebacterium Sulfolobus acidocaldarius. 295 1

Fast and slow muscles from the claws and abdomen of the American lobster Homarus americanus were examined for adenosine triphosphatase (ATPase) activity and for differences in myofibrillar proteins. Both myosin and actomyosin ATPase were correlated with fiber composition and contractile speed. Four distinct patterns of myofibrillar proteins observed in sodium dodecyl sulfate-polyacrylamide gels were distinguished by different assemblages of regulatory and contractile protein variants. A total of three species of troponin-T, five species of troponin-I, and three species of troponin-C were observed. Lobster myosins contained two groups of light chains (LC), termed "alpha" and "beta." There were three alpha-LC variants and two beta-LC variants. There were no apparent differences in myosin heavy chain, actin, and tropomyosin. Only paramyosin showed a pattern completely consistent with muscle fiber type: slow fibers contained a species (105 kD) slightly smaller than the principle variant (110 kD) in fast fibers. It is proposed that the type of paramyosin present could provide a biochemical marker to identify the fiber composition of muscles that have not been fully characterized. The diversity of troponin and myosin LC variants suggests that subtle differences in physiological performance exist within the broader categories of fast- and slow-twitch muscles.
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PMID:Heterogeneity of myofibrillar proteins in lobster fast and slow muscles: variants of troponin, paramyosin, and myosin light chains comprise four distinct protein assemblages. 315 73

There are alterations in the proteins synthesized during different stages of development of Schistosoma mansoni. The protein profiles at different stages were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. When stained by Coomassie blue, no significant differences were seen in protein profiles derived from cultured schistosomula from Days 0 to 6 and from adults. Newly synthesized proteins were detected by [35S]methionine incorporation. There were only a few differences in the protein profiles of schistosomula from Days 1 to 6 and from adults. Profiles derived from Day 0 schistosomula showed striking differences. Only a few proteins appear to be synthesized on Day 0 under these conditions. Schistosomula on Day 0 synthesized several minor proteins as well as a major protein of approximately 69,000 Da. This protein was immunoprecipitated by rabbit antiserum against bovine uncoating adenosine triphosphatase which recognizes the constitutive and induced 70,000 Da heat shock proteins in a wide variety of eukaryotic cells. More significant differences were observed when the newly synthesized proteins were analyzed by two dimensional gel electrophoresis. The profiles of newly synthesized proteins showed a specific repertoire of expression during the early stages of development in the parasite. A shift in temperature and medium during transformation from aquarium water to isotonic medium may initiate the synthesis of heat shock protein in these parasites.
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PMID:Schistosoma mansoni: protein composition and synthesis during early development; evidence for early synthesis of heat shock proteins. 358 70

Myosins from the following sources were purified by diethylaminoethyl-Sephadex chromatography: moytubes grown in vitro for 7-8 days, prepared from pectoralis muscles of 10-day old embryos, and breast and leg muscles from 16-day old embryos. The adenosine triphosphatase activities of these myosins were close to that of adult m. pectoralis myosin. The light chains of the embryonic myosins had the same mobilities in sodium dodecyl sulfate electrophoresis as those in adult pectoralis muscle myosin and were clearly distinguishable from those in myosin from tonic muscle m. latissimus dorsi anterior. The fastest light chain in embryonic muscle myosin-apparent mol wt 16,000-was present in smaller amounts than in adult myosin. The negative staining pattern of paracrystals of embryonic light meromyosin (LMM) was indistinguishable from that of adult fast muscle LMM. The significance of these results for differentiation of various muscle types has been discussed.
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PMID:Some properties of embryonic myosin. 412 Aug 61

Membranes of Micrococcus lysodeikticus possess antigens which are distinct from other cellular components such as cytoplasm, ribosomes, and cell walls. Only a few (two to three) components are found when dissociated membranes are examined by immunodiffusion and immunoelectrophoresis techniques. Membranes treated with 0.3% sodium dodecyl sulfate, 0.3% Triton X-100, trypsin, phospholipase A or C, or by sonic oscillation at pH 9.0, all showed the same pattern (three major bands) when examined against membrane antisera by immunoelectrophoresis. Immunological analysis of fractions isolated by sucrose gradient centrifugation or by polyacrylamide gel electrophoresis suggests that individual components cross-react. Antibodies to adenosine triphosphatase (EC 3.6.1.3) and fast-moving component are not removed by absorption with protoplasts. Removal of antibody to one of the membrane antigens by protoplast absorption indicated a surface location. Glutaraldehyde fixation of protoplasts resulted in the loss of membrane antigens detectable by immunodiffusion.
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PMID:Immunological properties of Micrococcus lysodeikticus membranes. 425 Jun 11

A dinitrophenol (DNP)-stimulated adenosine triphosphatase (ATPase) has been found in both the soluble and particulate fractions of the anaerobic sulfate-reducing bacterium, Desulfovibrio gigas. As the soluble ATPase was labile to storage, only the particulate enzyme was studied in detail. It was optimally stimulated by DNP at 4 mm, and activity was insensitive to inhibition by ouabain. The ATPase was stimulated by both Ca(2+) and Mg(2+), but the magnitude of the stimulation was dependent upon pH. In the presence of Ca(2+) the optimum pH was 6.5, whereas, in the presence of Mg(2+) the pH optimum was 8.0. However, under optimal conditions the activity was the same with either Mg(2+) or Ca(2+). Both adenosine triphosphate and guanosine triphosphate were hydrolyzed, but activity toward guanosine triphosphate was only one-tenth that observed with adenosine triphosphate.
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PMID:Dinitrophenol-stimulated adenosine triphosphatase activity in extracts of Desulfovibrio gigas. 425 19

The membrane adenosine triphosphatase (E.C. 3.6.1.3) from Escherichia coli has been solubilized with Triton X-100 and purified to near homogeneity. The purified enzyme has a sedimentation coefficient of 12.9S in a sucrose gradient, corresponding to a molecular weight of about 360,000. On electrophoresis in gels containing sodium dodecyl sulfate, it dissociates into subunits with apparent molecular weights of 60,000, 56,000, 35,000, and 13,000. The purified enzyme loses activity and breaks down into subunits when stored in the cold. Guanosine 5'-triphosphate and inosine 5'-triphosphate are alternative substrates. Ca(2+) and, to a small extent, Co(2+) or Ni(2+) will substitute for Mg(2+) in the reaction. The K(m) for Mg-adenosine triphosphate of the membrane-bound enzyme is 0.23 mM, and for the pure enzyme it is 0.29 mM. Azide is a noncompetitive inhibitor of both the membrane-bound enzyme and the pure enzyme. P(i) is a noncompetitive inhibitor of the solubilized enzyme. An antibody to the purified enzyme was obtained from rabbits. The antibody inhibits the solubilized enzyme and virtually all of the adenosine triphosphate hydrolysis by membranes from cells grown aerobically or anaerobically. The antibody also inhibits the adenosine triphosphate-stimulated pyridine nucleotide transhydrogenase (E.C. 1.6.1.1) of the E. coli membrane.
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PMID:Energy-transducing adenosine triphosphatase from Escherichia coli: purification, properties, and inhibition by antibody. 426 35

Myosin has been purified free of actin from Physarum actomyosin by a two step adaptation of the classical potassium iodide method for depolymerizing actin. On 12% sodium dodecyl sulfate (SDS) gels, the single major slowly moving protein band present in the calcium activated adenosine triphosphatase peak (90% pure) is associated with two fast moving bands of molecular weights of approximately 17,000 and 21,000 daltons, respectively. Densitometry shows the molar ratio of heavy chains to the 21,000 and 17,000 dalton chains on the gels to be 1:2:1. The highly purified myosin forms filaments up to 2.5 microm long in the presence of 5 mM magnesium and 0.05 M KCl. Calcium ions were not required for the formation of long filaments from this highly purified myosin. At low ionic strength (0.05 M KCl) the magnesium ATPase of the highly purified myosin is activated four- to tenfold by muscle actin. The extent of activation is a function of the actin concentration and levels off at high levels of actin. In 0.1 mM calcium salts the ATPase activity is approximately 60% of that in 1 mM EGTA. In summary, Physarum myosin is similar to a number of muscle myosins as well as to platelet and fibroblast myosin, which all possess light chains of two different molecular weights associated with the heavy chains. Under ionic conditions close to those in vivo, highly purified Physarum myosin aggregates into long filaments.
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PMID:Properties of Physarum myosin purified by a potassium iodide procedure. 427 79

The latency of Micrococcus lysodeikticus membrane-bound Mg(2+)-adenosine triphosphatase (ATPase) is expressed by the ratio of its activity assayed in the presence of trypsin ("total") versus the activity assayed in absence of the protease ("basal"). By isolating membranes in the presence of variable concentrations of Mg(2+) (50 mM, 10 mM, or none) and by washing them with different Mg(2+)- and ethylenediaminetetraacetic acid-containing tris(hydroxymethyl)aminomethane-hydrochloride buffers (pH 7.5), we showed that the enzyme latency was dependent on the environmental concentration of this divalent metal ion. Mg(2+) bound to at least two classes of sites. The binding of Mg(2+) to low-affinity sites (saturation at approximately 40 mM external Mg(2+)) induced a high basal ATPase activity, whereas its binding to medium-affinity sites (saturation at about 2 mM Mg(2+)) correlated with low basal activity and a very high stimulation by trypsin. Membranes with tightly bound Mg(2+) (high affinity?) revealed an intermediate behavior for the latency of M. lysodeikticus ATPase. The Mg(2+)/Ca(2+) antagonism as activators of the membrane ATPase was not directly related to Mg(2+) binding by the membranes. The efficiency of the ATPase release from M. lysodeikticus membrane by 3 mM tris(hydroxymethyl)aminomethane-hydrochloride buffer (pH 7.5) was inversely proportional to the concentration of external and/or bound Mg(2+). Deoxycholate (DOC) (1%) solubilized the ATPase from all types of membrane. All the soluble ATPases behaved as Ca(2+)-ATPases, but the DOC-soluble fractions showed degrees of latency like those of the original membranes. The DOC-soluble ATPase preparation revealed a vesicular structure and complex protein patterns by sodium dodecyl sulfate gel electrophoresis. We propose that ATPase latency is modulated via a Mg(2+)-ATPase-membrane complex.
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PMID:Membrane adenosine triphosphatase of Micrococcus lysodeikticus: effect of millimolar Mg2+ in modulating the properties of the membrane-bound enzyme. 427 71

High yields of mouse macrophage-melanocyte heterokaryons and macrophage-macrophage homokaryons were obtained through the virus-induced fusion of cells spread on a glass surface. After fusion there was a striking reorganization of cellular architecture by means of a colcemid-sensitive process. Heterokaryons were isolated through the use of differential trypsinization and many underwent division to form melanocyte-like hybrids. The selective uptake of dextran sulfate by macrophages served as a useful cytoplasmic marker in identifying hybrids. Many characteristic macrophage properties were altered in the heterokaryons. Within an hour of fusion macrophage nuclei became swollen, nucleoli were more prominent, and increased nuclear RNA synthesis occurred. 3 hr after fusion, a wave of DNA synthesis took place in the previously dormant macrophage nuclei. The fate of typical macrophage markers was examined in both heterokaryons and homokaryons. Macrophage homokaryons continued to exhibit active phagocytosis of sensitized erythrocytes, whereas this capacity was lost irreversibly in heterokaryons. The loss of phagocytic activity of heterokaryons occurred at an exponential rate and was accelerated by high concentrations of calf serum. Another macrophage surface marker, a divalent cation-dependent adenosine triphosphatase (ATPase), could be demonstrated histochemically on heterokaryons. Shortly after fusion, it was present in discrete regions, but it became more diffuse and disappeared within a day. Acid phosphatase-positive secondary lysosomes and retractile lipid droplets disappeared from heterokaryons but continued to accumulate in macrophage homokaryons. These observations indicate that typical macrophage properties cease to be expressed in heterokaryons, and melanocyte functions presumably predominate in heterokaryons and hybrids.
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PMID:Macrophage-melanocyte heterokaryons. I. Preparation and properties. 431 6


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