Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Chick embryo cells transformed by the Bryan "high titer" strain of Rous sarcoma virus (RSV-BH) are heavily vacuolated. A variety of microscopic techniques have been used demonstrating that the vacuoles are cytoplasmic, bounded by membrane, and are composed largely of water. Proteins, lipids, glycoproteins, glycolipids, glycosaminoglycans, glycogen, and nucleic acids were undetectable in the vacuoles. Physiological requirements for development of the vacuoles, and reversal of vacuolization, were examined in cells infected with a virus mutant, RSV-BH-Ta, which induces reversible temperature-dependent transformation. Na+ was the only component of the cell culture medium found essential for both the development and reversal of vacuoles. Glucose depletion or dinitrophenol treatment inhibited vacuolization, suggesting a possible energy requirement in the vacuolization process. Ouabain, an inhibitor of Na+-K+ ATPase, enhanced vacuolization, but a variety of other substances affecting cell surface components were in active. Two sugars, glucosamine and mannosamine, prevented the disappearance of vacuoles. The observations suggest that cellular vacuolization may be a normal physiological response to an increase in water and Na+, and, in the specific case of transformation by RSV-BH, may be relevant to the physiological basis for malignancy.
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PMID:Transformation of cells by rous sarcoma virus: cytoplasmic vacuolization. 5 59

During the log phase of growth both the active, ouabain-sensitive K+ uptake, measured as 86Rb+, and the sodium and potassium ion-activated ATPase ((Na+ + K+)-ATPase) activity of SV40-transformed 3T3 cells were 2.5-and 5,5-fold higher, respectively, than in untransformed 3T3 cells. A similar higher active K+ uptake was found for Rous sarcoma virus and SV40-transformed baby hamster kidney cells compared with untransformed BHK cells. The active K+ uptake in SV403T3 and normal 3T3 cells decreased when the growth rate of both cell types diminished. Reduction in ouabain-sensitive ATP hydrolysis only occurred later, however, when appreciable decreases in cell viability were seen. Arrhenius plots of the (Na+ + K+)-ATPase activity of SV403T3 cells indicated a discontinuity at 24 degrees, whereas no similar discontinuity was indicated for 3T3 cells. The consequences of elevated K+ transport and (Na+ + K+)-ATPase activity in transformed cells and the possibility that the increased activity might be related to differences inphospholipid fatty acyl chain fluidity are discussed.
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PMID:Increased ouabain-sensitive 86Rb+ uptake and sodium and potassium ion-activated adenosine triphosphatase activity in transformed cell lines. 16 82

The intracellular distribution of specific protease, plasminogen activator (PA), has been examined in Rous sarcoma virus-transformed chick embryo fibroblasts (RSV-CEF). Cellular homogenates were fractionated by differential centrifugation followed by sucrose gradient centrifugation. The activities and the percent distribution of a series of marker enzymes, specific for different subcellular organelles, were compared to those of PA. Normal CEF have been similarly fractionated and the relatively low amount of PA activity present in these cells has been analyzed in terms of its subcellular distribution. A membrane fraction was isolated from the RSV-CEF that contained the bulk of the PA activity and less than 8% of the total cellular protein. The specific activity of the PA in this fraction is 40-fold higher than that of a comparable fraction isolated from companion cultures of normal cells. This fraction contains little or no nuclear and cytoplasmic material and is contaminated only to a relatively small degree with mitochondria, lysosomes, endoplasmic reticulum. Significant amounts of a putative Golgi membrane marker are present in this fraction. The relatively high specific activities of Na+,K+-ATPase, 5'-nucleotidase, and [3H]fucose indicate that the fraction is enriched in surface membrane. Further purification of the fraction by equilibrium centrifugation on shallow sucrose gradients reduces further the contaminating activities and results in a PA distribution that closely parallels the distribution of the membrane enzyme, 5'-nucleotidase. PA was not released from its membrane association by hypotonic and hypertonic extraction and ultrasonication, while granule-bound enzymes were released by these treatments. The PA activity from hamster SV40 cells fractionated the same way as that of RSV-CEF. These results suggest that a protease that is dramatically enhanced upon malignant transformation is associated with "plasma membrane-like" elements of the cell and may serve as an intrinsic modifier of cell surface proteins after malignant transformation.
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PMID:Association of a protease (plasminogen activator) with a specific membrane fraction isolated from transformed cells. 99 59

T antigen is able to transactivate gene expression from the simian virus 40 (SV40) late promoter and from several other viral and cellular promoters. Neither the mechanisms of transactivation by T antigen nor the regions of T antigen required for this activity have been determined. To address the latter point, we have measured the ability of a set of SV40 large T antigen mutants to stimulate gene expression in CV-1 monkey kidney cells from the SV40 late promoter and Rous sarcoma virus (RSV) long terminal repeat (LTR) promoter. Transactivation, although reduced, was retained by an N-terminal 138-amino-acid fragment of T antigen. Mutants with alterations at various locations within the N-terminal 85 amino acids transactivated the RSV LTR promoter less well than did wild-type T antigen. Most of these were also partially defective in their ability to transactivate the SV40 late promoter. Two mutants with lesions in the DNA-binding domain that were unable to bind to SV40 DNA were completely defective for transactivation of both promoter, while a third mutant with a lesion in the DNA-binding domain which retained origin-binding activity transactivated both promoters as well as did wild-type T antigen. Only a low level of transactivation was seen with mutant T antigens which had lesions in or near the zinc finger region (amino acids 300 to 350). Mutations which caused defects in ATPase activity, host range/helper function, binding to p53, binding to the retinoblastoma susceptibility protein, or nuclear localization had little or no effect on transactivation. These results suggest that N-terminal portion of T antigen possesses an activation activity. The data are consistent with the idea that the overall conformation of T antigen is important for transactivation and that mutations in other regions that reduce or eliminate transactivation do so by altering the conformation or orientation of the N-terminal region so that its ability to interact with various targets is diminished or abolished.
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PMID:Mapping the transcriptional transactivation function of simian virus 40 large T antigen. 185 53

The Rous sarcoma virus (RSV)-transforming protein, pp60src, is a plasma membrane-associated tyrosine-specific protein kinase. A 36,000-Da cellular polypeptide (p36) which is phosphorylated at tyrosine in RSV-transformed chicken embryo fibroblasts (RSV-CEF) is also plasma membrane associated. To determine if p36 is directly phosphorylation and kinase activity in situ in the plasma membrane, src-dependent protein phosphorylation in membranes isolated from RSV-CEF has been characterized. These membrane preparations contained high ATPase and phosphoprotein phosphatase activities; but when sufficient concentrations of [gamma-32P]ATP were used, the phosphorylation of pp60src and the phosphorylation of p36 were linear for 1 min or more, and the initial rates of phosphorylation could therefore be determined. In membranes from RSV-CEF pp60src and p36 became phosphorylated predominantly at tyrosine, while in membranes from uninfected cells p36 was phosphorylated at low levels at serine. When membranes from RSV-CEF were preincubated with tumor-bearing rabbit (TBR) serum, the IgG became phosphorylated while the phosphorylation of p36 was inhibited, suggesting that p36 is directly phosphorylated by pp60src. Phosphorylation of pp60src, p36, and TBR-IgG was dependent on growth temperature in membranes from cells infected by a temperature-sensitive mutant, tsNY68, although some dependence on growth temperature was observed even with membranes from wild-type RSV-infected cells. However, at the nonpermissive temperature, tsNY68 pp60src retained 20-40% of its kinase activity, providing supporting for the proposal (B. M. Sefton, T. Hunter, and K. Beemon (1980, J. Virol, 33, 220-229) that transformation may result from a small quantitative change in pp60src activity. The phosphorylation of pp60src and its kinase activity were not coordinately affected by growth temperature or mutations within src, indicating that different factors affect the phosphoacceptor capacity and kinase activity of the protein.
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PMID:pp60src-dependent protein phosphorylation in membranes from Rous sarcoma virus-transformed chicken embryo fibroblasts. 299 19

A protein tyrosine kinase that phosphorylates both alpha and beta subunits of inactivated (Na+,K+)-ATPase from dog kidney was purified about 500-fold from Ehrlich ascites tumor cell membranes. The enzyme required divalent cations Mn2+, Mg2+, or Fe2+ but was inhibited by Cu2+ or Zn2+. The purified enzyme phosphorylated the beta subunit about five times faster than the alpha subunit of the (Na+,K+)-ATPase. The random polymer poly(Glu80Tyr20) was an excellent substrate while casein was only marginally phosphorylated. In contrast, the purified transforming gene product of Rous sarcoma virus phosphorylated all three substrates and the (Na+,K+)-ATPase was preferentially phosphorylated on the alpha subunit. The transforming gene product of Fujinami sarcoma visue and EGF receptor kinase from A431 cells phosphorylated (Na+,K+)-ATPase poorly whereas casein was an excellent substrate. The molecular weight of the partially purified protein tyrosine kinase from Ehrlich ascites tumor cells determined by gel filtration was about 60,000. One of two major phosphorylated phosphopeptides resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis had an Mr of 60 kDa, thus suggesting that it might be the autophosphorylated protein tyrosine kinase. A phosphatase that hydrolyzes phosphorylated histones or poly(Glu80Tyr20) was partially purified from the same membrane.
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PMID:A tyrosine-specific protein kinase from Ehrlich ascites tumor cells. 302 71

In addition to the previously described deoxyribonucleic acid (DNA) polymerase, DNA ligase, DNA exonuclease, and DNA endonuclease activities, purified virions of Schmidt-Ruppin strain of Rous sarcoma virus (SRV) have nucleotides and nucleotide kinase, phosphatase, hexokinase, and lactate dehydrogenase activities. The SRV virions have no glucose-6-phosphate dehydrogenase activity. All enzyme activities, but glucose-6-phosphate dehydrogenase and adenosine triphosphatase, were increased by disruption of the virions. The DNA polymerase, DNA ligase, and hexokinase activities had a higher specific activity in purified virion cores. It is suggested that during assembly virions of SRV may pick up cytoplasmic components which bind to virion proteins. The role of these components in viral replication is not known at present.
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PMID:Enzymes and nucleotides in virions of Rous sarcoma virus. 433 49

Cell lines resistant to ethidium bromide have been developed from cultured mammalian BHK21/C13 cells and these same cells transformed by Rous sarcoma virus (C13/B4). Cells resistant to 2 micrograms ethidium bromide per milliliter have been cloned. One clone of the control and one of the virus-transformed cell lines has been employed for characterization. The resistant cells, in the presence of 2 micrograms ethidium bromide/ml, grow at approximately the same rate as the untreated parental cells. The control cells possess a "normal" karyotype (44 chromosomes), while the corresponding ethidium bromide mutant has a reduced chromosome number of 41 and a number of translocations. The mitochondria displayed morphological alterations compared to the parental lines during the transition phase prior to the isolation of the ethidium bromide-resistant cells. The mitochondria of the ethidium bromide-resistant mutants appear somewhat enlarged with a normal morphology. The effect of ethidium bromide on selected respiratory enzymes in normal and virus-transformed ethidium bromide-resistant baby hamster kidney cells was determined. Ethidium bromide-resistant cells exhibited a depressed level of cytochrome aa3. This depression could not be reversed by growth in ethidium bromide-free media. Ethidium bromide-resistant cells possessed the same cytochrome b, c, and c1 levels per cell as their corresponding parental lines. Purified mitochondria isolated from virus-transformed ethidium bromide-resistant cells exhibited a depression in cytochrome oxidase-specific activity, while the ethidium bromide-resistant control cells did not. All cell lines studied showed a depression in NADH-ferricyanide and NADH-cytochrome c reductase-specific activities relative to their parental BHK21/C13 cells. No increase was observed in virus-transformed ethidium bromide-resistant cells. Ethidium bromide-resistant control cells exhibited a two-fold increase in oligomycin-insensitive adenosine triphosphatase activity relative to their parental cells. All of the cell lines studied possessed equivalent oligomycin-sensitive adenosine triphosphatase-specific activity except for the virus-transformed, dye-resistant mutant, whose activity was increased.
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PMID:Control and virus-transformed baby hamster kidney cells resistant to ethidium bromide. I. Characterization and the respiratory enzymes. 625 Oct 98

The increased rate of glucose uptake found in cells transformed by Rous sarcoma virus was shown to be enhanced relative to the changes in uptake induced in nontransformed cells by deprivation of glucose (deprivation derepression). Glucose-specific uptake sites were distinguished from glucose-galactose sites in nontransformed cells, and the capacities for glucose uptake and for galactose uptake were increased to about the same extent by the exclusion of glucose from the cell culture medium. Deprivation derepression occurred without a requirement for new RNA or protein synthesis, suggesting that preexisting inactivate uptake sites were activated. Deprivation derepression could be mimicked by the treatment of cells with adenosine triphosphatase activators, and adenosine triphosphate levels were reduced in glucose-deprived cells and in cells treated with adenosine triphosphatase activators. Cells transformed by the Bryan strain of Rous sarcoma virus were unresponsive to addition of high concentrations of glucose, to glucose starvation, or to treatment with adenosine triphosphatase activators, and the relative capacity for glucose uptake in these transformed cells was enhanced much more than the capacity of galactose uptake. It was concluded that cells infected by the Bryan strain of rous sarcoma virus in the process of transformation selectively synthesize more sites specific for glucose uptake. Lower levels of adenosine triphosphate found in transformed cells possibly contribute to a chronic derepression of uptake sites.
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PMID:Increased glucose uptake capacity of Rous-transformed cells and the relevance of deprivation derepression. 626 Mar 48

Rates of uptake and intracellular concentrations of monovalent cations were measured in virus-transformed and nontransformed chick embryo (CE) cells. Uptake of 22Na+ into cells transformed by the BH strain of Rous sarcoma virus (RSV-BH) (CE-BH) was about double the rate of uptake into CE cells, or cells transformed by the Schmidt-Ruppin strain (RSV-SR): CE-SR. Likewise, the rate of efflux of 22Na+ was greater in CE-BH cells than in CE or CE-SR cells. The greater permeability of CE-BH cells to Na+ was apparent in higher intracellular Na+ concentrations. Experiments with cells exhibiting temperature-dependent transformation showed that new RNA and protein synthesis was a requirement for the acquisition of increased Na+ permeability, suggesting that the change is an indirect effect of the virus-coded transformation-inducing protein. Rates of 86Rb+ uptake, used as a measure of K+ influx, were indistinguishable in CE, CE-BH, and CE-SR cells. Also, equilibrium intracellular levels of 86Rb+ were similar in transformed and nontransformed cells, as were observed concentrations of K+. Also, no differences in ATPase activity, as indicated by ouabain binding or temperature sensitivity, were observed. We conclude that monovalent cations play no direct role in RSV-induced transformation, although the higher levels of Na+ in CE-BH cells may be responsible for other distinguishing biochemical features of these cells.
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PMID:Sodium and rubidium uptake in cells transformed by Rous sarcoma virus. 626 Aug 19


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