A novel vanadium transporter of the Nramp family expressed at the vacuole of vanadium-accumulating cells of the ascidian Ascidia sydneiensis samea
Biochimica et Biophysica Acta (BBA) - General Subjects 1810 巻 4 号
457-464 頁
2011-04 発行
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| ファイル情報(添付) | |
| タイトル ( eng ) |
A novel vanadium transporter of the Nramp family expressed at the vacuole of vanadium-accumulating cells of the ascidian Ascidia sydneiensis samea
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| 作成者 |
Michibata Hitoshi
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| 収録物名 |
Biochimica et Biophysica Acta (BBA) - General Subjects
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| 巻 | 1810 |
| 号 | 4 |
| 開始ページ | 457 |
| 終了ページ | 464 |
| 抄録 |
Background: Vanadium is an essential transition metal in biological systems. Several key proteins related to vanadium accumulation and its physiological function have been isolated, but no vanadium ion transporter has yet been identified.
Methods: We identified and cloned a member of the Nramp/DCT family of membrane metal transporters (AsNramp) from the ascidian Ascidia sydneiensis samea, which can accumulate extremely high levels of vanadium in the vacuoles of a type of blood cell called signet ring cells (also called vanadocytes). We performed immunological and biochemical experiments to examine its expression and transport function. Results: Western blotting analysis showed that AsNramp was localized at the vacuolar membrane of vanadocytes. Using the Xenopus oocyte expression system, we showed that AsNramp transported VO2+ into the oocyte as pH-dependent manner above pH 6, while no significant activity was observed below pH 6. Kinetic parameters (Km and Vmax) of AsNramp-mediated VO2+ transport at pH 8.5 were 90 nM and 9.1 pmol/oocyte/h, respectively. A rat homolog, DCT1, did not transport VO2+ under the same conditions. Excess Fe2+, Cu2+, Mn2+ or Zn2+ inhibited the transport of VO2+. Conclusions: AsNramp was revealed to be a novel VO2+/H+ antiporter, and we propose that AsNramp mediates vanadium accumulation coupled with the electrochemical gradient generated by vacuolar H+-ATPase in vanadocytes. General Significance: This is the first report of identification and functional analysis on a membrane transporter for vanadium ions. |
| 著者キーワード |
Membrane protein
Transport metals
Vanadium
Ascidian
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| 内容記述 |
This work was supported in part by Grants-in-Aid from the Ministry of Education, Culture, Sports, Science and Technology, Japan (#17370026, #18570070, #20570070, and #21570077).
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| NDC分類 |
生物科学・一般生物学 [ 460 ]
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| 言語 |
英語
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| 資源タイプ | 学術雑誌論文 |
| 出版者 |
Elsevier B.V.
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| 発行日 | 2011-04 |
| 権利情報 |
Copyright (c) 2011 Elsevier B.V. All rights reserved.
This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
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| 出版タイプ | Author’s Original（十分な品質であるとして、著者から正式な査読に提出される版） |
| アクセス権 | オープンアクセス |
| 収録物識別子 |
[ISSN] 0304-4165
[NCID] AA11522932
[DOI] 10.1016/j.bbagen.2010.12.006
[DOI] http://doi.org/10.1016/j.bbagen.2010.12.006
～の異版である
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