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

Plasma membranes were isolated from the ameba Acanthamoeba castellanii by low-speed velocity centrifugation followed by equilibrium centrifugation in a sucrose gradient. The isolated membranes had a high ratio of sterol to phospholipid (0.98 moles/mole) and of phospholipid to protein (0.43 mg/mg). The plasma membranes had very low concentrations of DNA, RNA, lipid inositol, and glycerides. Glycolipids and glycoproteins were enriched in the plasma membranes relative to their concentrations in the whole cell. The plasma membranes were also judged to be of high purity by the absence, or very low level, of enzymatic activities considered to be indicative of other cell membranes, and by electron microscope examination. Alkaline phosphatase and 5'-nucleotidase activities were enriched in the plasma membranes 13-fold relative to the whole homogenate and had higher specific activities in the plasma membranes than in any other cell fractions. A Mg(++) adenosine triphosphatase (ATPase) was enriched sixfold in the plasma membranes relative to the whole homogenate. The phospholipids of the plasma membranes contained more phosphatidylethanolamine and phosphatidylserine and less phosphatidylcholine than did the phospholipids of the whole cells. There were differences in the fatty acid compositions of corresponding phospholipids in the plasma membranes and whole cells but no difference in the ratios of total saturated to unsaturated fatty acids. The membranes of phagosomes isolated from amebae that had ingested polystyrene latex had essentially the same phospholipid, sterol, and enzymatic composition as plasma membranes.
 ...
PMID:Plasma and phagosome membranes of Acanthamoeba castellanii. 432 20

Discrete sites of adenosine triphosphatase (ATPase) activity were demonstrated within the nucleoli of unfixed cultured human fibroblasts (IMR90, VA13, and AG2804 cells) by an adaptation, for electron microscopic cyto-chemistry, of Wachstein and Meisel's lead nitrate method. The majority of nucleoli contained more than one ATPase-positive region, but the total ATPase-positive material appeared to occupy only a minor portion of the nucleolar volume. These regions were roughly spherical with an irregular contour, and at times appeared to be components of perinucleolar chromatin or to be located adjacent to nucleolar interstices. The distribution of these regions within the nucleolus and their segregation by actinomycin D suggested that the ATPase-positive regions correspond to the fibrillar centers, which represent nucleolar organizer regions. The cytochemically demonstrable nucleolar ATPase was strictly dependent on the presence of divalent cations. Optimal reactions was seen at 5 mM Mg2+, but near optimal activity was obtained with lower concentrations of Mg2+ in the presence of Ca2+. Calcium alone and Mn2+ alone produced suboptimal reaction. Studies with different nucleoside phosphates as reaction substrates showed that the enzyme is specific for adenosine derivatives, ATP and dATP being equally good substrates. Guanosine triphosphate, cytidine triphosphate, uridine triphosphate, and d-thymidine triphosphate were ineffective as substrates, as were nucleoside mono- and diphosphates and other phosphate esters tested. It is suggested that the cytochemical ATPase reaction visualized the regions of the nucleolus in which ribosomal DNA of intranucleolar chromatin is undergoing conformational alterations.
 ...
PMID:Visualization of nucleolar substructure in cultured human fibroblasts by magnesium-activated adenosine triphosphatase reaction. 611 91

Binding of both synthetic poly(A) and naturally occurring poly(A) (+)mRNA as well as DNA to microtubule protein is mediated by microtubule-associated proteins; tubulin itself is not capable of binding these polymers. Bovine brain microtubule protein from immature animals was found to have a significantly lower capacity to bind poly(A) than microtubule protein from old animals. On the other hand, "old" microtubule protein binds DNA more efficiently than "immature" microtubule protein. Microtubule-associated protein 2 [preferred binding site for DNA] and tau proteins [preferred binding site for poly (A)] are specifically phosphorylated by a microtubule-associated, cAMP-dependent protein kinase. It was found that the affinity of microtubule protein for poly(A) is markedly decreased by autophosphorylation of the protein; in the case of DNA, the decrease in affinity was less. Autophosphorylation of "immature" microtubule proteins diminished the binding capacity for poly(A) to a greater extent than do "old" proteins. Scatchard plot analysis revealed that microtubule-protein possesses two different binding sites for poly(A). The corresponding dissociation constants were found to be increased in the phosphorylated system, but phosphorylation does not appear to alter the total number of binding sites. Compared to immature animals, microtubule protein from "old" bovine brains was found to have a reduced number of binding sites for poly(A), whereas the values of the dissociation constants remain unchanged. In contrast to total microtubule protein and homogeneous microtubule-associated protein 2, only one kind of binding site for poly(A) could be detected in homogeneous tau protein. No influence of different RNA or DNA species on microtubule protein-associated cAMP-dependent protein kinase, adenosine triphosphatase and guanosine triphosphatase activities could be detected.
 ...
PMID:Binding of polyribonucleotides and polydeoxyribonucleotides to bovine brain microtubule protein: age-dependent modulation via phosphorylation of high-molecular-weight microtubule-associated proteins and tau proteins. 614 31

Quercetin is a naturally occurring flavonoid, chemically related to cromolyn. Quercetin has been shown to inhibit antigen- and mitogen-induced histamine release from rat mast cells and basophils of subjects with hay fever, to increase cyclic adenosine monophosphate (AMP) in Ehrlich ascites tumor cells and to inhibit phosphodiesterase and certain adenosine triphosphatase (ATPase) systems. We have studied the effect of quercetin on mouse T cell responses. When 5 x 10(-6) to 5 x 10(-5) M quercetin is present throughout either allogeneic mixed leukocyte culture (MLC) or cytotoxic T lymphocyte (CTL) assay culture, inhibition of in vitro CTL generation or effector function results, respectively (inhibition is 75-100% at 2 x 10(-5) M and 100% at 5 x 10(-5) M). Quercetin also inhibits concanavalin A-induced DNA synthesis. Addition of Cu2+ strongly blocks the effects of quercetin in all systems tested, in a concentration dependent fashion, while Mg2+ and Ca2+ have little or no effect and Mn2+ and Co2+ have a significant but slight blocking effect on quercetin-mediated inhibition of both CTL generation and function. In kinetic studies, evidence was obtained for the existence of a major quercetin-sensitive step in CTL induction, between 3 and 24 hr of the MLC.
 ...
PMID:Quercetin inhibition of the induction and function of cytotoxic T lymphocytes. 621 17

A yeast nuclear pet mutant of Saccharomyces cerevisiae lacking any detectable mitochondrial F1-ATPase activity was genetically complemented upon transformation with a pool of wild type genomic DNA fragments carried in the yeast Escherchia coli shuttle vector YEp 13. Plasmid-dependent complementation restored both growth of the pet mutant on a nonfermentable carbon source as well as functional mitochondrial ATPase activity. Characterization of the complementing plasmid by plasmid deletion analysis indicated that the complementing gene was contained on adjoining BamH1 fragments with a combined length of 3.05 kilobases. Gel analysis of the product of this DNA by in vitro translation in a rabbit reticulocyte lysate programmed with yeast mRNA hybrid selected by the plasmid revealed a product which could be immunoprecipitated by antisera against the beta subunit of the yeast mitochondrial ATPase complex. A comparison of the protein sequence derived from partial DNA sequence analysis indicated that the beta subunit of the yeast mitochondrial ATPase complex exhibits greater than 70% conservation of protein sequence when compared to the same subunit from the ATPase of E. coli, beef heart, and chloroplast. The gene coding the beta subunit (subunit 2) of yeast mitochondrial adenosine triphosphatase is designated ATP2. The utilization of cloned nuclear structural genes of mitochondrial proteins for the analysis of the post-translational targeting and import events in organelle assembly is discussed.
 ...
PMID:Nuclear genes coding the yeast mitochondrial adenosine triphosphatase complex. Isolation of ATP2 coding the F1-ATPase beta subunit. 622 76

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.
 ...
PMID:Sulfhydryl groups of the F1 adenosine triphosphatase of Escherichia coli and the stoichiometry of the subunits. 623 Sep 95

Thyroid status was altered by use of a low-iodine-perchlorate (PC) regimen and either reversal with NaI or injections of L-3,5,3'-triiodothyronine (T3). The PC regimen decreased renal and hepatic oxygen consumption (QO2), alpha-glycerophosphate dehydrogenase (alpha-GPDH), and Na+-K+-dependent adenosine triphosphatase (Na-K-ATPase) to comparable extents (25 vs. 23%, 26 vs. 39%, and 41 vs. 51%, respectively). Administration of T3 to hypothyroid rats elicited dose-dependent increases in hepatic and renal cortical QO2, ouabain-sensitive oxygen consumption (QO2(t)), alpha-GPDH, and Na-K-ATPase activities. The half-maximal increases in all of the response parameters in both kidney and liver were obtained at dosages of 6-32 micrograms T3/100 g body wt. The equivalences in the renal cortical vs. hepatic responses were indicated by correlation coefficients of approximately 0.97. Kidney and liver nuclei also showed similar high-affinity binding of 125I-T3-K1/2 = 29 vs. 18 micrograms T3/100 g body wt, and Nmax = 1.8 vs. 2.1 ng T3/mg DNA. The patterns of the responses plotted as a function of T3 occupancy of the high-affinity nuclear binding sites were indistinguishable in kidney and liver. These results imply similar modes of action of T3, probably initiated at the nuclear level, in both kidney and liver.
 ...
PMID:Nuclear binding of T3 and effects of QO2, Na-K-ATPase, and alpha-GPDH in liver and kidney. 625 44

The gene product of the pleiotropic lon (also called capR) locus in Escherichia coli, the CapR protein, is an ATP hydrolysis-dependent protease and a nonspecific nucleic acid-binding protein. We demonstrated that it is also a DNA-stimulated adenosine triphosphatase (ATPase). This new activity is distinct from the protease-associated ATPase activity and occurs in the absence of proteolytic substrate. The reaction requires the presence of a divalent cation and has a pH optimum of 8.0. The products of the reaction are ADP and inorganic phosphate. No adenylation or phosphorylation of the DNA or proteins was detected. The maximum rate of ATP hydrolysis occurs in the presence of supercoiled (form I) DNA. Relaxed circles (form II), double-stranded DNA, and single-stranded DNA are less effective in promoting ATPase activity, whereas RNA is inactive. The DNA-stimulated ATPase activity is inhibited by a mutationally altered form of the CapR protein called the CapR9 protein. The interaction of the CapR and CapR9 subunits suggests that this enzymatic activity of the CapR protein is oligomeric in the presence of DNA. Our in vitro experiments indicate a possible role for nucleic acids in the regulation of all lon (capR) activity.
 ...
PMID:DNA-stimulated ATPase activity on the lon (CapR) protein. 632 86

We have recently demonstrated by electron microscopic cytochemical methods that unfixed human fibroblasts exhibit intense MG2+ dependent adenosine triphosphatase (nATPase) activity in circumscribed areas of the cell nucleoli. The nATPase was specific for ATP and dATP and was inhibited by other ribonucleoside triphosphates. Its intranucleolar localization relative to nucleolar chromatin, and segregation into nucleolar zones after actinomycin treatment of the cells, suggested that the reaction took place in fibrillar centers. This ATPase has now been further characterized by electron microscopic cytochemistry. It was determined that short fixation permitted retention of most of the ATPase activity, and that the enzyme was active at high ionic strength (up to 400 mM KCl), but that the enzyme activity was very sensitive to elevated temperatures. DNA dependence of the enzyme was shown by inhibition of the reaction by DNase pretreatment in parallel with the removal of DNA from the cell, while pretreatment with RNase had no significant effect. The nATPase activity was also selectively inhibited by treatment of the cells with antagonists of the B subunit of DNA gyrase, novobiocin, and coumermycin, but not by nalidixic or oxolinic acids, which interfere with the A subunit of gyrase. Inhibitors of RNA synthesis, actinomycin D and aminonucleoside of puromycin, potentiate rather than inhibit nATPase reaction. The results suggest that nATPase functions to alter the degree of supercoiling or catenation of nucleolar organizer DNA, and is in reality a DNA topoisomerase that hydrolyzes ATP during its action.
 ...
PMID:DNA dependence and inhibition by novobiocin and coumermycin of the nucleolar adenosine triphosphatase (ATPase) of human fibroblasts. 646 Aug 2

The effects of chronic alcohol consumption on nitrosamine metabolism in vivo, DNA synthesis and repair, and carcinogen-induced preneoplasia were studied in rat liver. Following a single injection of different doses of 14C-N-nitrosodimethylamine, there was no significant difference between controls and ethanol-pretreated rats in the alkylation pattern of cellular protein nor in the levels of the alkylation products 7-methylguanine and O6-methylguanine isolated from liver DNA. O6-Methylguanine-specific DNA repair was also unchanged. An increase in the number and size of foci staining negative for adenosine triphosphatase and/or positive for gamma-glutamyltranspeptidase was observed in rats treated intermittently with ethanol and N-nitrosomorpholine. The numbers of clear-cell and mixed-cell foci were also increased. An ethanol-mediated enhancement of DNA synthesis, which was ascertained by different methods, may be related to this cocarcinogenic action of the alcohol. Ethanol, however, failed to demonstrate promoting activity. Long-term treatment of carcinogen pretreated rats with ethanol, according to the classical initiation-promotion protocol, had no effect on the incidence of preneoplastic foci in liver.
 ...
PMID:The mechanism of cocarcinogenic action of ethanol in rat liver. 653 12


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>