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ID 39961
本文ファイル
著者
Michibata, Hitoshi
キーワード
Membrane protein
Transport metals
Vanadium
Ascidian
NDC
生物科学・一般生物学
抄録(英)
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.
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).
掲載誌名
Biochimica et Biophysica Acta (BBA) - General Subjects
1810巻
4号
開始ページ
457
終了ページ
464
出版年月日
2011-04
出版者
Elsevier B.V.
ISSN
0304-4165
NCID
出版者DOI
言語
英語
NII資源タイプ
学術雑誌論文
広大資料タイプ
学術雑誌論文
DCMIタイプ
text
フォーマット
application/pdf
著者版フラグ
author
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/
関連情報URL(IsVersionOf)
http://doi.org/10.1016/j.bbagen.2010.12.006
部局名
理学研究科