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)

Two membrane fractions prepared from the Ehrlich ascites-tumor cell show non-identical stimulatory responses to certain amino acids in their Mg+2 -dependent activity to cleave ATP, despite the presence of ouabain and the absence of Na+ or K+. The first of these, previously described, shows little (Na+ + K+)-ATPase activity, and is characteristicallly stimulated by the presence of certain diamino acids with low pK2, and at pH values suggesting that the cationic forms of these amino acids are effective. The evidence indicates that these effects are not obtained through occupation of the kinetically discernible receptor site serving characteristically for the uphill transport of these amino acids into the Ehrlich cell. The second membrane preparation was purified with the goal of concentrating the (Na+ +K+)-ATPase activity. It also is stimulated by the model diamino acid, 4-amino-1-methylpiperidine-4-carboxylic acid, and several ordinary amino acids. The diamino acids were most effective at pH values where the neutral zwitterionic forms might be responsible. Among the optically active amino acids tested, the effects of ornithine and leucine were substantially stronger for the L than for the D isomers. The list of stimulatory amino acids again corresponds poorly to any single transport system, although the possibility was not excluded that stimulation might occur for both preparations by occupation of a membrane site which ordinarily is kinetically silent in the transport sequence. The high sensitivity to deoxycholate and to dicyclohexylcarbodiimide of the hydrolytic activity produced by the presence of L-ornithine and 4-amino-1-methyl-piperidine-4-carboxylic acid suggests that the stimulatory effect is not merely a general intensification of the background Mg+ -dependent hydrolytic activity.
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PMID:Amino acid stimulation of ATP cleavage by two Ehrlich cell membrane preparations in the presence of ouabain. 0 67

(1) The mitochondrial ATPase (EC 3.6.1.3) Ehrlich ascites cell mitochondria, was inhibited by D-glucose under physiological concentrations of ATP. The generation of ADP by the mitochondrial bound hexokinase, seems to be the reason for the D-glucose inhibitory effect. Reversal of the inhibitory effect of ADP on Ehrlich ascites cell mitochondria ATPase by an ATP-regenerating system was achieved. (2) Dissociation of mitochondrial bound hexokinase from the mitochondria eliminated the inhibitory effect of D-glucose. Rebinding of the hexokinase to the mitochondria regenerated the D-glucose inhibitory effect on Ehrlich ascites cell mitochondria ATPase. (3) Bioflavonoids such as quercetin inhibit the mitochondrial hexokinase activity, but do not change the mitochondrial ATPase activity of isolated Ehrlich ascites tumor cell mitochondria. (4) The inhibitory effect of bioflavonoids on mitochondrial bound hexokinase activity is shown to be dissociable from the ascites tumor cell mitochondria and seems to be associated with regulatory rather than catalitic sites of the enzyme.
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PMID:Bioflavonoid regulation of ATPase and hexokinase activity in Ehrlich ascites cell mitochondria. 1 95

Dependence of the HCO--3-stimulated ATPase activity from nuclei and mitochondria of rat ovary ascites tumor cells on pH and concentration of bicarbonate ions was studied. PCMB, NaN3, NaCNS, NaClO4 and NaF inhibited the HCO--3-stimulated ATPase activity. The properties of HCO--3-sensitive ATPase from rat ovary ascites tumor cells were similar to that of HCO--3-ATPases from other tissues.
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PMID:[HCO3-stimulated adenosine triphosphatase in rat ovarian tumor cells]. 2 52

Bioflavonoids are potent inhibitors of lactate transport in Ehrlich ascites tumor cells. The most effective bioflavonoids have four to five hydroxyl groups. Sugar substitution at carbon three, or reduction of the double bond between carbons two and three, decreases their inhibitory activity. Quercetin, the most extensively studied of these compounds, inhibits lactate efflux by 50% at 0.1 micrograms/mg of protein. On addition of quercetin to glycolyzing Ehrlich ascites tumor cells, lactate accumulates inside the cell and the intracellular pH drops. Total lactate production is also inhibited. Nigericin prevents the internal acidification that occurs in the presence of quercetin and also reduces the inhibition of glycolysis. Thus, it appears that inhibition of lactate efflux can affect glycolysis through a lowering of the intracellular pH. The inhibitory effect of quercetin on glycolysis can be explained by its effect on lactate efflux and its previously reported effect on the Na+--K+ ATPase [Suolinna, E.--M., et al. (1974) J. Natl. Cancer Inst. 53, 1515].
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PMID:Inhibition of lactate transport and glycolysis in Ehrlich ascites tumor cells by bioflavonoids. 3 32

Injection of RF virus (RFV), a papovavirus isolated from human urine, into newborn Syrian hamsters induced subcutaneous sarcomas in 50% of the recipients with 18- to 48-week latent periods. Transplantation of 2 X 10(6) primary RFV-induced tumor cells into weaning hamsters caused tumors in 100% of the recipients within 1-2 weeks. Continuous tissue culture cell lines were established from two primary tumors; one of these was transplantable. An in vitro-transformed continuous cell line (RF-194) obtained by infection of primary hamster embryo fibroblasts with RFV was transplantable in weaning hamsters. Neither infectious RFV nor virion antigens were detected in transformed cells. No RFV was recovered when transformed cells were fused with permissive, human embryo kidney cells by means of inactivated Sendai virus. Immunoperoxidase staining was used to show that all three RFV-transformed cell lines contained an intranuclear T-antigen closely similar to that of simian virus 40(SV40)-infected cells. Most hamsters (84%) with primary or transplanted RFV tumors responded with antibodies that reacted with RFV T-antigen and the T-antigen of SV40-infected cells. Likewise, hamster antisera against SV40 T-antigen cross-reacted with RFV T-antigen. Adsorption of RFV T-antisera with an excess of lyophilized SV40-transformed cells removed all detectable activity against SV40 T-antigen but left significant activity against RFV T-antigen. The reciprocal adsorption produced an antiserum spedicic for SV40 T-antigen. Thus human and simian papovavirus T-antigens were related but immunologically separable.
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PMID:Induction of tumors in Syrian hamsters by a human renal papovavirus, RF strain. 6 61

HeLa cells infected with the nondefective adenovirus type 2-simian virus 40 hybrid viruses Ad2+ND1 or Ad2+ND2 were analyzed for cell surface location of the SV40-specific hybrid virus proteins by indirect immunofluorescence microscopy. Two different batches of sera from SV40 tumor-bearing hamsters, serum from SV40 tumor-bearing mice, or two different antisera prepared against purified sodium dodecyl sulfate-denatured SV40 T-antigen, respectively, were used. All sera were shown to exhibit comparable T- and U-antibody titers and to specifically immunoprecipitate the SV40-specific proteins from cell extracts of Ad2+ND2-infected cells. Whereas analysis of living, hybrid virus-infected HeLa cells did not yield conclusive results, analysis of Formalin-fixed cells resulted in positive cell surface fluorescence with both Ad2+ND1- and Ad2+ND2-infected HeLa cells when antisera prepared against sodium dodecyl sulfate-denatured SV40 T-antigen were used as first antibody. In contrast, sera from SV40 tumor-bearing animals were not or only very weakly able to stain the surfaces of these cells. The fact that the tumor sera had comparable or even higher T- and U-antibody titers than the antisera against sodium dodecyl sulfate-denatured T-antigen but were not able to recognize SV40-specific proteins on the cell surface suggests that SV40 tumor-specific transplantation antigen may be an antigenic entity different from T- or U-antigen.
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PMID:Cell surface location of simian virus 40-specific proteins on HeLa cells infected with adenovirus type 2-simian virus 40 hybrid viruses Ad2+ND1 and Ad2+ND2. 9 Jan 74

Embryonal rhabdomyosarcomas from the nasopharynx of two children were examined by histochemical methods commonly applied to muscle biopsies. These stains included nicotinamide adenine dinucleotide-tetrazolium reductase (NADH-TR), succinate dehydrogenase (SDH), PAS, PAS-diastase, myophosphorylase, calcium-mediated adenosine triphosphatase (ATPase) preincubated at high and low pH, and oil red O. Myofibrils were easily identified with ATPase and blood vessel walls were also stained. NADH-TR clearly showed longitudinal and cross-striations that were not seen with H&E or PTAH stains. The modified Gomori trichrome stain additionally contributed to the recognition of myofibrils. Some techniques of muscle histochemistry applied to fresh frozen sections of tumor tissue may provide evidence of muscular differentiation in otherwise poorly differentiated sarcomas for a more accurate diagnosis of rhabdomyosarcoma.
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PMID:Diagnostic value of histochemistry in embryonal rhabdomyosarcoma. 9 52

Membrane glycoproteins have been studied in the normal lactating mammary gland and R3230 AC mammary tumor of the rat. Plasma membrane-enriched fractions were obtained from these tissues by discontinuous sucrose gradient centrifugation of a microsomal preparation from the tissue homogenates. The lightest membrane fractions (F-1 and F-2) have the greatest enrichment of plasma membrane markers, with a 14- to 20-fold purification of 5'-nucleotidase and Na+-K+ -adenosine triphosphatase over the homogenate values in both tumor and normal tissues for F-1. Electron microscopy shows smooth membrane vesicles for these fractions. Polypeptide analysis by acrylamide gel electrophoresis shows essentially the same patterns for F-1 and F-2 and only relatively minor differences between membrane components of tumor and normal tissues. Glycoprotein analysis of the polyacrylamide gels by periodate-Schiff staining indicates more dramatic differences. Membrane Fraction F-1 from normal tissue contains two major glycoproteins, GP-II and GP-III, while Fractions F-2 and F-3 contain an additional glycoprotein, GP-I, with a higher apparent molecular weight. In the tumor, the component corresponding to GP-III is decreased or absent and a new component GP-IV is seen at a lower apparent molecular weight.
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PMID:Membrane glycoprotein differences between normal lactating mammary tissue and the R3230 AC mammary tumor. 12 79

A Mg2+- and Ca2+-stimulated adenosine triphosphatase (ATPase) at the outer surface of intact Ehrlich ascites tumor cells is described. A surface-bound adenosine triphosphate (ATP)-splitting activity at a lower rate was also demonstrated in the absence of Ca2+ but with Mg2+, Na+, and K+ present in the isotonic medium. Hence, when part of the Mg2+ was exchanged for Ca2+, a marked increase of the ATP-splitting activity was observed. The stimulatory effect of Ca2+ was seen only if both Na+ and K+ were present in the isotonic incubation medium. Thus, the enzyme activity was Mg2+- and Ca2+-dependent. Ca2+, together with the monovalent cations was inhibitory compared with Mg2+ under similar conditions. The apparent Km for ATP for the Mg2+-stimulated ATPase is 0.05 mM, while that of the Mg2+- and Ca2+-stimulated enzyme is 0.10 mM. The Vmax of the former is 0.8 mu-mole per 100 mg Schneider protein per 30 sec compared with 1.92 mu-moles per 100 mg Schneider protein per 30 sec for the latter. The calculated Km for the Mg2+- and Ca2+-stimulated ATPase after subtraction of the Mg2+-stimulated part is 0.22 mM. Ethacrynic acid and N-ethylmaleimide both inhibited the Mg2+- and Ca2+-stimulated ATPase by about 10 percent, while the ouabain inhibition was 15 percent. Cytochalasin B did not influence the enzyme activity, whereas La3+ had a slight stimulatory effect.
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PMID:A Mg2+- and Ca2+-stimulated adenosine triphosphatase at the outer surface of Ehrlich ascites tumor cells. 12 5

Certain bioflavonoids inhibit the glycolysis of variety of tumor cells by interfering with the generation of adenosine diphosphate and inorganic phosphate which are required for glycolysis. Tetra- and pentahydroxy flavones with hydroxyl groups as 3, 3', 4', 5, and 7 (e.g., quercetin) are the most active. They inhibit the activity of isolated Na+-K+-adenosinetriphosphatase of the plasma membrane and of mitochondrial adenosinetriphosphatase, but under appropriate conditions do not interfere with the ion transport increase the the translocation efficiency of the ion pump. It was shown that in several tumor cells loosely coupled ion pumps are responsible for the high rate of aerobic glycolysis, the effect of quercetin on the growth of several cell lines was examined. Since bicarbonate and serum albumin were found to counteract the effect of quercetin, the cells were grown in tissue cultures at low concentrations of these compounds. Pronounced inhibition of growth was observed at 5 to 20 mug of quercetin per ml of growth medium.
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PMID:The effect of flavonoids on aerobic glycolysis and growth of tumor cells. 12 7


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