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)

Cell culture conditions were devised that selectively supported growth of 13 or 14 gestation day F344 rat ureteric bud, the renal collecting duct anlagen. These same conditions also inhibited the growth of metanephrogenic mesenchyme, precursor of structures proximal to the duct. Isolated buds were cultured in Ham's F12 medium supplemented with epidermal growth factor, selenium, insulin, hydrocortisone, prostaglandin E1, transferrin, and triiodothyronine; fetal bovine serum (1%) was required for continuous propagation. Cultured cells were epithelial in morphology and formed domes. By electron microscopy, many structural characteristics of highly differentiated cells were evident: numerous mitochondria, Golgi apparatus, extensive endoplasmic reticulum, an occasional cilium, intracytoplasmic filaments, polarized formation of microvilli, and gap junctions. Histochemistry revealed considerable functional differentiation as well. Cultured bud cells, adult collecting duct, and fetal duct anlagen were positive for acid phosphatase, membrane-localized ATPase, and nonspecific esterase. Bud cells and fetal duct anlagen expressed high levels of gamma-glutamyl transpeptidase activity while adult collecting duct exhibited slight activity. In addition, immunocytochemical observation of intermediate filament expression revealed the presence of epithelial cytokeratins but absence of mesenchymal vimentin in cultured bud cells and fetal and adult collecting ducts. These results indicate that the culture conditions described can maintain the partially differentiated fetal collecting duct anlagen in a state consistent with its embryonal derivation, and therefore may be useful in culture studies of renal differentiation.
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PMID:Selective growth in culture of fetal rat renal collecting duct anlagen. Morphologic and biochemical characterization. 286 2

A monoclonal antibody to vacuolar H+ATPase isolated from bovine kidney medulla was produced and characterized by immunoprecipitation and immunocytochemistry. The antibody, immobilized on beads, specifically immunoprecipitated both solubilized N-ethylmaleimide-sensitive ATPase activity and proton-transporting vesicles from renal microsomes; control experiments with an "irrelevant" monoclonal antibody showed no immunoprecipitated activity. By fluorescent immunocytochemistry, the antibody stained the membranes of intracellular vacuolar compartments in LLC-PK1 cells. Immunocytochemical staining showed that the monoclonal antibody colocalized partially with N-(3-[2,4-dinitrophenyl)amino)propyl)-N-(3-amino-propyl)methylamine, a probe for acidic compartments, with the endocytic markers dextran and transferrin, with the lysosomal probe alpha 2-macroglobulin, and with clathrin. The anti-vacuolar H+ATPase antibody showed no colocalization with staining for mitochondrial H+ATPase. The anti-vacuolar H+ATPase antibody should serve as a specific probe for examining the distribution and dynamics of the vacuolar proton pump in renal epithelial cells.
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PMID:Production and characterization of a monoclonal antibody to vacuolar H+ATPase of renal epithelia. 289 Jun 33

Coated vesicles bearing the transferrin-transferrin receptor complex were isolated from rabbit reticulocytes by freeze-thaw cell lysis, followed by differential centrifugation with pelleting of vesicles at 100,000 g. Electronmicroscopy demonstrated the vesicles to have the characteristic morphology of coated vesicles, including the appearance of triskelions. The protein composition of the vesicles as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis included transferrin, transferrin receptor, and proteins of apparent mol wt of approximately 180,000, 140,000, 100,000, and 47,000 daltons. The 180,000 and 100,000 mol wt proteins were identified as clathrin and coated vesicle assembly factor proteins, respectively, by Western blot analyses. The vesicles had a Mg2+-dependent ATPase with a specific activity of approximately 8.5 nmoles ATP converted/min/mg vesicle protein. The vesicles could acidify the intravesicular space, as evidenced by the stimulation of the Mg2+-ATPase by the protonophore FCCP. Reticulocytes appear to be an excellent source of coated vesicles and as such should provide a model for studying the endocytosis of transferrin and the steps of iron uptake that proceed in these vesicles.
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PMID:Rabbit reticulocyte coated vesicles carrying the transferrin-transferrin receptor complex: I. Purification and partial characterization. 295

The entering of T-lymphocytes into the DNA-synthesizing phase was marked by three consecutive signals, i.e., antigenic influence, interleukin-2, a specific T-lymphocyte cell growth factor, and non-specific serum growth-promoting factors, in the first place, transferrin. This system was used for the study of effects of virus SV40 T-antigen on cell mitotic cycle. Purified T-antigen was injected consecutively into T-lymphocytes, using erythrocyte ghost vesicles instead of one of control signals. It was shown that T-antigen cannot simulate the antigenic response but simulates the effect of interleukin-2, a specific growth-promoting factor. However, both normally proliferating T-lymphocytes and T-antigen-induced lymphocytes showed an absolute requirement for transferrin and, apparently, for other nonspecific growth-promoting factors. It was assumed that the polymorphism of tumours induced by papovaviruses is determined by the ability of their "early" proteins to imitate the effects of their specific growth-promoting factors on the cells.
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PMID:[Ability of virus SV40 T-antigen to simulate the effect of specific T lymphocyte growth factor--interleukin-2]. 301 63

The inhibition of glycolysis in tumor cells by methionine requires that the cells be incubated with methionine for several hours in the presence of serum. We now show that in the case of confluent rat-1 fibroblasts transfected with the ras gene the serum can be substituted by insulin and insulin-like growth factor I or II. No other growth factor tested was effective. In subconfluent ras cells additional growth factors (transferrin and high density lipoproteins) were required for maximal inhibition of glycolysis by methionine. Exploration of the mechanism of action of methionine revealed that the accumulation of [35S]methionine into rat-1 fibroblasts was only marginally increased by insulin. We propose that methionine inhibits an adenosine triphosphatase activity because addition of low concentrations of Nonidet P-40 greatly enhanced glycolysis even in the presence of methionine, suggesting that it did not affect the glycolytic enzymes directly. Methionine also affected growth both in monolayer and soft agar. Rat-1 fibroblasts transfected with the ras gene were markedly more sensitive to methionine than cells transfected with the myc gene.
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PMID:Effect of growth factors and methionine on glycolysis and methionine transport in rat fibroblasts and fibroblasts transfected with myc and ras genes. 308 Dec 58

Hepatocytes of transgenic mouse fetuses harboring SV40 virus transforming gene sequences in the SV delta e-MGH fusion gene construct 202 driven by the mouse metallothionein (MT-I) enhancer [R. D. Palmiter, H. Y. Chen, A. Messing, and R. L. Brinster (1985) Nature (London) 316, 457-460] were cultured at Day 19 of gestation and established as a differentiated line expressing albumin and alpha-fetoprotein (AFP) mRNAs. Hepatocyte line FMH-202 contains integrated SV40 sequences, expresses SV40 T-antigen genes, and exhibits unlimited growth potential because it has been cultured 18 months without apparent decrease in cell viability or in growth rate that could suggest the occurrence of a crisis period. Immortalized cells multiply in chemically defined medium deficient in arginine with transferrin plus insulin, whereas EGF, insulin, and transferrin are obligatory requirements for fetal or newborn mouse hepatocyte multiplication in primary cultures. Cells did not grow in agar and were not tumorigenic in nude mice. Their immortalized, nonmalignant phenotype was further documented by low saturation densities of confluent monolayers showing no overgrowth, and by growth arrest in the absence of insulin with subsequent induction of DNA synthesis and resumption of cell growth in response to insulin. Thus, it appears that immortalized SV40 T-antigen-expressing hepatocytes are present in the liver of the transgenic mice. However, at later points in liver development the transforming activity of T-antigen becomes apparent and leads to hepatocellular carcinoma formation in vivo.
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PMID:Immortalized differentiated hepatocyte lines derived from transgenic mice harboring SV40 T-antigen genes. 328 99

The activity of Na,K-ATPase was measured in brain microsomes as the function of increasing concentrations of vanadyl (VOSO4, V4+) and the vanadate (NaVO3, V5+) ions. Both forms of vanadium inhibited the Na,K-ATPase activity with high affinity -Ki (vanadate) = 3 X 10(-7)M and Ki (vanadyl = 1 X 10(-6)M. The stability of V4+ in ATPase reaction media (Tris buffers) was measured by electron spin resonance spectroscopy. Without any reducing agent, V4+ was quickly oxidised by atmospheric oxygen. When a reducing agent such as dithiothreitol was added, the V4+ was stable for at least 30 min and the inhibition pattern of Na,K-ATPase by V4+ was not changed. The blocking effect of V4+ in the presence of dithiothreitol was counteracted by pre-incubation with equimolar concentrations of transferrin or 100 times excess of noradrenaline. The regulation of brain Na,K-ATPase by vanadate may be represented by competition between low-capacity inhibitory binding sites localized on the enzyme molecule and high-capacity sites of intracellular proteins. Preferential binding of vanadyl to the latter type of sites will decrease the intracellular concentration of the free metal and thus eliminate the enzyme inhibition.
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PMID:Vanadyl (VO2+) and vanadate (VO-3) ions inhibit the brain microsomal Na,K-ATPase with similar affinities. Protection by transferrin and noradrenaline. 608 31

Primary cultures of rabbit-kidney epithelial cells derived from purified proximal tubules were maintained without fibroblast overgrowth in a hormone-supplemented serum-free medium (Medium RK-1). A hormone-deletion study indicated that the primary cultures derived from purified rabbit proximal tubules required all of the three supplements in Medium RK-1 (insulin, transferrin, and hydrocortisone) for optimal growth but did not grow in response to EGF and T3. In contrast, the epithelial cells in primary cultures derived from an unpurified preparation of rabbit kidney tubules and glomeruli grew in response to EGF and T3, as well as insulin, transferrin, and hydrocortisone. These observations suggest that kidney epithelial cells derived from different segments of the nephron grow differently in response to hormones and growth factors. Differentiated functions of the primary cultures derived from proximal tubules were examined. Multicellular domes were observed, indicative of transepithelial solute transport by the monolayers. The proximal tubule cultures also accumulated alpha-methylglucoside (alpha-MG) against a concentration gradient. However, little or no alpha-MG accumulation was observed in the absence of Na+. Metabolic inhibitor studies also indicated that alpha-MG uptake by the primaries is an energy-dependent process, and depends upon the activity of the Na+/K+ ATPase. Phlorizin at 0.1 mM significantly inhibited 1 mM alpha-MG uptake whereas 0.1 mM phloretin did not have a significant inhibitory effect. Similar observations have been made concerning the Na+-dependent sugar-transport system located on the lumenal side of the proximal tubule, whereas the Na+-independent sugar transporter on the peritubular side is more sensitive to inhibition by phloretin than phlorizin. The cultures also exhibited PTH-sensitive cyclic AMP synthesis and brush-border enzymes typical of proximal cells. However, the activities of the enzymes leucine aminopeptidase, alkaline phosphatase, and gamma-glutamyl-transpeptidase were lower in the cultures than in purified proximal-tubule preparations from which they are derived.
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PMID:Characterization of primary rabbit kidney cultures that express proximal tubule functions in a hormonally defined medium. 629 32

The kinetics in tumor cells and various factors affecting the tumor accumulation of 67Ga-citrate and 201Tl-chloride were studied in vitro. 67Ga was taken up gradually by tumor cells and its excretion from the cells decreased with time. 201Tl was taken up rapidly by tumor cells. Its excretion was very rapid, indicating that the two nuclides had entirely different kinetics in tumor cells. The uptake of 201Tl by culture cells correlated with that of 42KCl and was inhibited by Ouabain. 201Tl was hardly taken up by nonviable tumor cells. These facts indicate that active transport involving Na-K ATPase is involved in the tumor accumulation of 201Tl. The uptake of 67Ga and 201Tl by tumor cells was not affected by the administration of anticancer agents. The uptake of 67Ga by tumor cells was dependent upon the concentration of transferrin in the medium, which apparently plays a role as one of the pathways of tumor accumulation of 67Ga.
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PMID:Accumulation of radioisotopes with tumor affinity. II. Comparison of the tumor accumulation of 67Ga-citrate and 201Tl-chloride in vitro. 645 47

The significance of the H(+)-ATPase in iron absorption by rabbit reticulocytes is explored using isolated endosomes, effects of inhibitors, and the purified proton pump. We have recently reported H(+)-ATPase-mediated iron transfer across a liposomal membrane (Li et al., 1994). In this report, the effect of H(+)-ATPase inhibitors on iron mobilization is investigated at pH 6.0 in the presence of 15 microM FCCP in order to dissociate 59Fe(III) from transferrin and eliminate the kinetic effects of acidification by the ATPase. Iron transport by isolated endosomes is decreased 50% by the cation pore inhibitor dicyclohexylcarbodiimide (DCCD) for ascorbate-mediated iron mobilization and increased by 40-50% when NADH and ferrocyanide are used as electron donors. In contrast, the ATPase hydrolysis inhibitors N-methylmaleimide (NEM) and 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (NBD) increase iron mobilization when NADH and ferrocyanide are used as reductants but have negligible effects for ascorbate. The differential inhibition or enhancement by DCCD, NEM, and NBD with respect to the reductants used for mobilization indicates that the H(+)-ATPase may be involved in the multiple pathways or iron transport found in isolated rabbit reticulocyte endosomes. Effects of inhibitors of ATP hydrolysis suggest significant structural interactions between the proton pump and sites for iron binding and/or reduction. The isolated H(+)-ATPase binds iron as revealed by using nondenaturing electrophoretic and chromatographic methods. One class of iron binding sites is suggested to be the 17.5 kDa proton pore subunits of the H(+)-ATPase which also covalently react with DCCD.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Iron binding, a new function for the reticulocyte endosome H(+)-ATPase. 771 Oct 32


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