Journal Article

Characterization of an Anion Transporter in the Plasma Membrane of Barley Roots

Kousei Yamashita, Yoko Yamamoto and Hideaki Matsumoto

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 37, issue 7, pages 949-956
Published in print October 1996 | ISSN: 0032-0781
e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/oxfordjournals.pcp.a029044
Characterization of an Anion Transporter in the Plasma Membrane of Barley Roots

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To examine the relationship between H+-ATPase and the transport of anions, we investigated the effects of various inhibitors on the activity of the H+-ATPase, the transport of protons, and the transport of Cl- ions using plasma membrane vesicles prepared from barley roots. Some inhibitors, namely, 4,4-diisothiocyano-2,2-stilbene disulfonate (DIDS) and Zn2+ ions markedly inhibited H+- ATPase activity. Other compounds, such as phenylglyoxal (PGO) and niflumic acid (NIF), inhibited H+-ATPase activity by 20-30%, while anthracene-9-carboxylate (A-9-C) and tetraethylammonium chloride (TEA-Cl) had little effect on this activity. The ATP-dependent acidification of the interior of vesicles was strongly dependent on the presence of permeant anions, such as chloride (Cl-) and nitrate (NO3-), and it was completely inhibited by 0.2 mM NIF. Other compounds, namely, A-9-C of 0.1 mM and TEA-Cl of 10 mM, did not affect H+-transport activity. The inhibition of H+-transport activity by NIF was observed even when the activity was assayed in the presence of KCl, KNO3, or bis-tris-propane (BTP)-Cl. Using 36cl, we quantified Cl--transport activity by measuring the uptake of Cl- ions into the plasma membrane vesicles. The uptake depended on the potential difference across the membrane that was generated by H+-ATPase; it was enhanced by an inside-positive potential gradient. At 0.1 mM, NIF completely blocked the voltage-dependent Cl--transport activity. From these properties of the Cl- transporter and the inhibition of H+-transport activity by NIF, we suggest that H+-transport activity across the plasma membrane might be modulated by the transport of anions via a NIF-sensitive anion-permeable transporter that acts to collapse the inside-positive potential generated by H+-ATPase.

Keywords: Cl- uptake; Hordeum vulgare L.; H+--transport activity; Niflumic acid; Plasma membrane

Journal Article.  0 words. 

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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