The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Masaru Kawamura - One of the best experts on this subject based on the ideXlab platform.
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Transient association of the sarcoplasmic reticulum Ca2+ ATPase with the Na+/K+-ATPase and H+/K+-ATPase beta-subunits during its biogenesis in Xenopus oocytes.
Journal of Cell Science, 2003Co-Authors: Shunsuke Noguchi, Nobuhito Sone, Masaru KawamuraAbstract:We examined the effect of the β-subunits of the Na + /K + and H + /K + ATPases on the biogenesis of the sarcoplasmic reticulum (SR) Ca 2+ ATPase in Xenopus oocytes. Oocytes were simultaneously injected with cRNAs for both the SR Ca 2+ ATPase and the β-subunit of the Na + /K + or the H + /K + ATPase. Immunoprecipitation with antiserum specific for the β-subunit of the Na + /K + or the H + /K + ATPase yielded not only the respective β-subunit but also the SR Ca 2+ ATPase, indicating that the SR Ca 2+ ATPase was associated with theβ -subunits of the Na + /K + and the H + /K + ATPases. Pulse-chase experiments revealed that the complex between the SR Ca 2+ ATPase and the β-subunit of the Na + /K + ATPase was formed transiently and dissociated during the course of maturation. This is the first report that demonstrates the association of the SR Ca 2+ ATPase with the β-subunit of the Na + /K + and H + /K + ATPases.
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Transient association of the sarcoplasmic reticulum Ca2+ ATPase with the Na+/K+-ATPase and H+/K+-ATPase beta-subunits during its biogenesis in Xenopus oocytes.
Journal of cell science, 2003Co-Authors: Shunsuke Noguchi, Nobuhito Sone, Masaru KawamuraAbstract:We examined the effect of the beta-subunits of the Na+/K+ and H+/K+ ATPases on the biogenesis of the sarcoplasmic reticulum (SR) Ca2+ ATPase in Xenopus oocytes. Oocytes were simultaneously injected with cRNAs for both the SR Ca2+ ATPase and the beta-subunit of the Na+/K+ or the H+/K+ ATPase. Immunoprecipitation with antiserum specific for the beta-subunit of the Na+/K+ or the H+/K+ ATPase yielded not only the respective beta-subunit but also the SR Ca2+ ATPase, indicating that the SR Ca2+ ATPase was associated with the beta-subunits of the Na+/K+ and the H+/K+ ATPases. Pulse-chase experiments revealed that the complex between the SR Ca2+ ATPase and the beta-subunit of the Na+/K+ ATPase was formed transiently and dissociated during the course of maturation. This is the first report that demonstrates the association of the SR Ca2+ ATPase with the beta-subunit of the Na+/K+ and H+/K+ ATPases.
Shunsuke Noguchi - One of the best experts on this subject based on the ideXlab platform.
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Epigallocatechin-3-gallate is an inhibitor of Na+, K(+)-ATPase by favoring the E1 conformation.
Biochemical Pharmacology, 2009Co-Authors: Hideo Ochiai, Kazuo Takeda, Shiori Soeda, Yoshikazu Tahara, Hitoshi Takenaka, Shunsuke Noguchi, Masumi Inoue, Yutaro Hayashi, Silvia SchwarzAbstract:Abstract Four catechins, epigallocatechin-3-gallate, epigallocatechin, epicatechin-3-gallate, and epicatechin, inhibited activity of the Na + ,K + -ATPase. The two galloyl-type catechins were more potent inhibitors, with IC 50 values of about 1 μM, than were the other two catechins. Inhibition by epigallocatechin-3-gallate was noncompetitive with respect to ATP. Epigallocatechin-3-gallate reduced the affinity of vanadate, shifted the equilibrium of E 1 P and E 2 P toward E 1 P, and reduced the rate of the E 1 P to E 2 P transition. Epigallocatechin-3-gallate potently inhibited membrane-embedded P-type ATPases (gastric H + ,K + -ATPase and sarcoplasmic reticulum Ca 2+ -ATPase) as well as the Na + ,K + -ATPase, whereas soluble ATPases (bacterial F 1 -ATPase and myosin ATPase) were weakly inhibited. Solubilization of the Na + ,K + -ATPase with a nonionic detergent reduced sensitivity to epigallocatechin-3-gallate with an elevation of IC 50 to 10 μM. These results suggest that epigallocatechin-3-gallate exerts its inhibitory effect through interaction with plasma membrane phospholipid.
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Transient association of the sarcoplasmic reticulum Ca2+ ATPase with the Na+/K+-ATPase and H+/K+-ATPase beta-subunits during its biogenesis in Xenopus oocytes.
Journal of Cell Science, 2003Co-Authors: Shunsuke Noguchi, Nobuhito Sone, Masaru KawamuraAbstract:We examined the effect of the β-subunits of the Na + /K + and H + /K + ATPases on the biogenesis of the sarcoplasmic reticulum (SR) Ca 2+ ATPase in Xenopus oocytes. Oocytes were simultaneously injected with cRNAs for both the SR Ca 2+ ATPase and the β-subunit of the Na + /K + or the H + /K + ATPase. Immunoprecipitation with antiserum specific for the β-subunit of the Na + /K + or the H + /K + ATPase yielded not only the respective β-subunit but also the SR Ca 2+ ATPase, indicating that the SR Ca 2+ ATPase was associated with theβ -subunits of the Na + /K + and the H + /K + ATPases. Pulse-chase experiments revealed that the complex between the SR Ca 2+ ATPase and the β-subunit of the Na + /K + ATPase was formed transiently and dissociated during the course of maturation. This is the first report that demonstrates the association of the SR Ca 2+ ATPase with the β-subunit of the Na + /K + and H + /K + ATPases.
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Transient association of the sarcoplasmic reticulum Ca2+ ATPase with the Na+/K+-ATPase and H+/K+-ATPase beta-subunits during its biogenesis in Xenopus oocytes.
Journal of cell science, 2003Co-Authors: Shunsuke Noguchi, Nobuhito Sone, Masaru KawamuraAbstract:We examined the effect of the beta-subunits of the Na+/K+ and H+/K+ ATPases on the biogenesis of the sarcoplasmic reticulum (SR) Ca2+ ATPase in Xenopus oocytes. Oocytes were simultaneously injected with cRNAs for both the SR Ca2+ ATPase and the beta-subunit of the Na+/K+ or the H+/K+ ATPase. Immunoprecipitation with antiserum specific for the beta-subunit of the Na+/K+ or the H+/K+ ATPase yielded not only the respective beta-subunit but also the SR Ca2+ ATPase, indicating that the SR Ca2+ ATPase was associated with the beta-subunits of the Na+/K+ and the H+/K+ ATPases. Pulse-chase experiments revealed that the complex between the SR Ca2+ ATPase and the beta-subunit of the Na+/K+ ATPase was formed transiently and dissociated during the course of maturation. This is the first report that demonstrates the association of the SR Ca2+ ATPase with the beta-subunit of the Na+/K+ and H+/K+ ATPases.
Michael Forgac - One of the best experts on this subject based on the ideXlab platform.
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Regulation of V-ATPase assembly and function of V-ATPases in tumor cell invasiveness
Biochimica et biophysica acta, 2016Co-Authors: Christina Mcguire, Kristina Cotter, Laura A. Stransky, Michael ForgacAbstract:V-ATPases are ATP-driven proton pumps that function within both intracellular compartments and the plasma membrane in a wide array of normal physiological and pathophysiological processes. V-ATPases are composed of a peripheral V(1) domain that hydrolyzes ATP and an integral V(0) domain that transports protons. Regulated assembly of the V-ATPase represents an important mechanism of regulating V-ATPase activity in response to a number of environmental cues. Our laboratory has demonstrated that glucose-dependent assembly of the V-ATPase complex in yeast is controlled by the Ras/cAMP/PKA pathway. By contrast, increased assembly of the V-ATPase during dendritic cell maturation involves the PI-3 kinase and mTORC1 pathways. Recently, we have shown that amino acids regulate V-ATPase assembly in mammalian cells, possibly as a means to maintain adequate levels of amino acids upon nutrient starvation. V-ATPases have also been implicated in cancer cell survival and invasion. V-ATPases are targeted to different cellular membranes by isoforms of subunit a, with a3 targeting V-ATPases to the plasma membrane of osteoclasts. We have shown that highly invasive human breast cancer cell lines express higher levels of the a3 isoform than poorly invasive lines and that knockdown of a3 reduces both expression of V-ATPases at the plasma membrane and in vitro invasion of breast tumor cells. Moreover, overexpression of a3 in a non-invasive breast epithelial line increases both plasma membrane V-ATPases and in vitro invasion. Finally, specific ablation of plasma membrane V-ATPases in highly invasive human breast cancer cells using either an antibody or small molecule approach inhibits both in vitro invasion and migration. These results suggest that plasma membrane and a3-containing V-ATPases represent a novel and important target in the development of therapeutics to limit breast cancer metastasis. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi.
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Localization of subunit C (Vma5p) in the yeast vacuolar ATPase by immuno electron microscopy
FEBS Letters, 2006Co-Authors: Zhenyu Zhang, Michael Forgac, Takao Inoue, Stephan WilkensAbstract:Abstract Vacuolar ATPases (V1V0-ATPases) function in proton translocation across lipid membranes of subcellular compartments. We have used antibody labeling and electron microscopy to define the position of subunit C in the vacuolar ATPase from yeast. The data show that subunit C is binding at the interface of the ATPase and proton channel, opposite from another stalk density previously identified as subunit H [Wilkens S., Inoue T., and Forgac M. (2004) Three-dimensional structure of the vacuolar ATPase – Localization of subunit H by difference imaging and chemical cross-linking. J. Biol. Chem. 279, 41942–41949]. A picture of the vacuolar ATPase stalk domain is emerging in which subunits C and H are positioned to play a role in reversible enzyme dissociation and activity silencing.
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arg 735 of the 100 kda subunit a of the yeast v ATPase is essential for proton translocation
Proceedings of the National Academy of Sciences of the United States of America, 2001Co-Authors: Shoko Kawasakinishi, Tsuyoshi Nishi, Michael ForgacAbstract:The vacuolar (H+)-ATPases (V-ATPases) are ATP-dependent proton pumps that acidify intracellular compartments and pump protons across specialized plasma membranes. Proton translocation occurs through the integral V0 domain, which contains five different subunits (a, d, c, c′, and c"). Proton transport is critically dependent on buried acidic residues present in three different proteolipid subunits (c, c′, and c"). Mutations in the 100-kDa subunit a have also influenced activity, but none of these residues has proven to be required absolutely for proton transport. On the basis of previous observations on the F-ATPases, we have investigated the role of two highly conserved arginine residues present in the last two putative transmembrane segments of the yeast V-ATPase a subunit (Vph1p). Substitution of Asn, Glu, or Gln for Arg-735 in TM8 gives a V-ATPase that is fully assembled but is totally devoid of proton transport and ATPase activity. Replacement of Arg-735 by Lys gives a V-ATPase that, although completely inactive for proton transport, retains 24% of wild-type ATPase activity, suggesting a partial uncoupling of proton transport and ATP hydrolysis in this mutant. By contrast, nonconservative mutations of Arg-799 in TM9 lead to both defective assembly of the V-ATPase complex and decreases in activity of the assembled V-ATPase. These results suggest that Arg-735 is absolutely required for proton transport by the V-ATPases and is discussed in the context of a revised model of the topology of the 100-kDa subunit a.
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structure mechanism and regulation of the clathrin coated vesicle and yeast vacuolar h ATPases
The Journal of Experimental Biology, 2000Co-Authors: Michael ForgacAbstract:The vacuolar H(+)-ATPases (or V-ATPases) are a family of ATP-dependent proton pumps that carry out acidification of intracellular compartments in eukaryotic cells. This review is focused on our work on the V-ATPases of clathrin-coated vesicles and yeast vacuoles. The coated-vesicle V-ATPase undergoes trafficking to endosomes and synaptic vesicles, where it functions in receptor recycling and neurotransmitter uptake, respectively. The yeast V-ATPase functions to acidify the central vacuole and is necessary both for protein degradation and for coupled transport processes across the vacuolar membrane. The V-ATPases are multisubunit complexes composed of two functional domains. The V(1) domain is a 570 kDa peripheral complex composed of eight subunits of molecular mass 73-14 kDa (subunits A-H) that is responsible for ATP hydrolysis. The V(o) domain is a 260 kDa integral complex composed of five subunits of molecular mass 100-17 kDa (subunits a, d, c, c' and c") that is responsible for proton translocation. To explore the function of individual subunits in the V-ATPase complex as well as to identify residues important in proton transport and ATP hydrolysis, we have employed a combination of chemical modification, site-directed mutagenesis and in vitro reassembly. A central question concerns the mechanism by which vacuolar acidification is controlled in eukaryotic cells. We have proposed that disulfide bond formation between conserved cysteine residues at the catalytic site of the V-ATPase plays an important role in regulating V-ATPase activity in vivo. Other regulatory mechanisms that are discussed include reversible dissociation and reassembly of the V-ATPase complex, changes in the tightness of coupling between proton transport and ATP hydrolysis, differential targeting of V-ATPases within the cell and control of the Cl(-) conductance that is necessary for vacuolar acidification.
Hitoshi Michibata - One of the best experts on this subject based on the ideXlab platform.
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Subunit C of the Vacuolar-Type ATPase from the Vanadium-Rich Ascidian, Ascidia sydneiensis samea, Rescued the pH Sensitivity of Yeast vma5 Mutants
Marine biotechnology (New York N.Y.), 2001Co-Authors: Tatsuya Ueki, Kan Kanamori, Taro Uyama, Hitoshi MichibataAbstract:A vanadium-accumulating ascidian, Ascidia sydneiensis samea, expresses vacuolar-type H+-ATPases (V-ATPases) on the vacuole membrane of the vanadium-containing blood cells known as vanadocytes. Previously, we showed that the contents of their vacuoles are extremely acidic and that a V-ATPase-specific inhibitor, bafilomycin A1, neutralized the contents of the vacuoles. To understand the function of V-ATPase in vanadocytes, we isolated complementary DNA encoding subunit C of V-ATPase from vanadocytes because this subunit has been known to be responsible for the assembly of V-ATPases and to regulate the ATPase activity of V-ATPases. The cloned cDNA was 1443 nucleotides in length, and encoded a putative 384 amino acid protein. By expressing the ascidian cDNA for subunit C under the control of a galactose-inducible promoter, the pH-sensitive phenotype of the corresponding vma5 mutant of a budding yeast was rescued. This result showed that the ascidian cDNA for subunit C functioned in yeast cells.
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ISOLATION OF CDNAS ENCODING SUBUNITS A AND B OF THE VACUOLAR-TYPE ATPase FROM THE VANADIUM-RICH ASCIDIAN, ASCIDIA SYDNEIENSIS SAMEA
Zoological Science, 1998Co-Authors: Tatsuya Ueki, Kan Kanamori, Taro Uyama, Hitoshi MichibataAbstract:Abstract Vacuolar-type H+-ATPases (V-ATPases), which are composed of at least ten different subunits, can generate a proton-motive force by hydrolyzing ATP and acidify the contents of various intracellular organelles. Subunits A and B of V-ATPase have been detected immunologically in ascidian blood cells, predominantly in signet ring cells (vanadocytes), which accumulate vanadium in their vacuoles. The action of V-ATPase in ascidian blood cells has been demonstrated by the fact that bafilomycin A1, a specific inhibitor of V-ATPases, inhibits the acidification of the vacuoles of vanadocytes. As the next step in studying the function of V-ATPase in vanadocytes, we isolated cDNAs encoding subunits A and B of V-ATPase from the blood cells of an ascidian, Ascidia sydneiensis samea. The nucleotide sequences of the cDNAs for subunits A and B encoded proteins of 619 and 509 amino acids, respectively, both of which were highly conserved among organisms.
Nobuhito Sone - One of the best experts on this subject based on the ideXlab platform.
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Transient association of the sarcoplasmic reticulum Ca2+ ATPase with the Na+/K+-ATPase and H+/K+-ATPase beta-subunits during its biogenesis in Xenopus oocytes.
Journal of Cell Science, 2003Co-Authors: Shunsuke Noguchi, Nobuhito Sone, Masaru KawamuraAbstract:We examined the effect of the β-subunits of the Na + /K + and H + /K + ATPases on the biogenesis of the sarcoplasmic reticulum (SR) Ca 2+ ATPase in Xenopus oocytes. Oocytes were simultaneously injected with cRNAs for both the SR Ca 2+ ATPase and the β-subunit of the Na + /K + or the H + /K + ATPase. Immunoprecipitation with antiserum specific for the β-subunit of the Na + /K + or the H + /K + ATPase yielded not only the respective β-subunit but also the SR Ca 2+ ATPase, indicating that the SR Ca 2+ ATPase was associated with theβ -subunits of the Na + /K + and the H + /K + ATPases. Pulse-chase experiments revealed that the complex between the SR Ca 2+ ATPase and the β-subunit of the Na + /K + ATPase was formed transiently and dissociated during the course of maturation. This is the first report that demonstrates the association of the SR Ca 2+ ATPase with the β-subunit of the Na + /K + and H + /K + ATPases.
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Transient association of the sarcoplasmic reticulum Ca2+ ATPase with the Na+/K+-ATPase and H+/K+-ATPase beta-subunits during its biogenesis in Xenopus oocytes.
Journal of cell science, 2003Co-Authors: Shunsuke Noguchi, Nobuhito Sone, Masaru KawamuraAbstract:We examined the effect of the beta-subunits of the Na+/K+ and H+/K+ ATPases on the biogenesis of the sarcoplasmic reticulum (SR) Ca2+ ATPase in Xenopus oocytes. Oocytes were simultaneously injected with cRNAs for both the SR Ca2+ ATPase and the beta-subunit of the Na+/K+ or the H+/K+ ATPase. Immunoprecipitation with antiserum specific for the beta-subunit of the Na+/K+ or the H+/K+ ATPase yielded not only the respective beta-subunit but also the SR Ca2+ ATPase, indicating that the SR Ca2+ ATPase was associated with the beta-subunits of the Na+/K+ and the H+/K+ ATPases. Pulse-chase experiments revealed that the complex between the SR Ca2+ ATPase and the beta-subunit of the Na+/K+ ATPase was formed transiently and dissociated during the course of maturation. This is the first report that demonstrates the association of the SR Ca2+ ATPase with the beta-subunit of the Na+/K+ and H+/K+ ATPases.
