JXB Advance Access originally published online on May 31, 2005
Journal of Experimental Botany 2005 56(417):1897-1903; doi:10.1093/jxb/eri184
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RESEARCH PAPER |
Distinct pH regulation of slow and rapid anion channels at the plasma membrane of Arabidopsis thaliana hypocotyl cells
Institut des Sciences du Végétal, CNRS UPR 2355, F-91198 Gif sur Yvette, France
* Present address and to whom correspondence should be sent: Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA. Fax: +1 858 534 7108. E-mail: jcolcomb{at}biomail.ucsd.edu
Variations in both intracellular and extracellular pH are known to be involved in a wealth of physiological responses. Using the patch-clamp technique on Arabidopsis hypocotyl cells, it is shown that rapid-type and slow-type anion channels at the plasma membrane are both regulated by pH via distinct mechanisms. Modifications of pH modulate the voltage-dependent gating of the rapid channel. While intracellular alkalinization facilitates channel activation by shifting the voltage gate towards negative potentials, extracellular alkalinization shifts the activation threshold to more positive potentials, away from physiological resting membrane potentials. By contrast, pH modulates slow anion channel activity in a voltage-independent manner. Intracellular acidification and extracellular alkalinization increase slow anion channel currents. The possible role of these distinct modulations in physiological processes involving anion efflux and modulation of extracellular and/or intracellular pH, such as elicitor and ABA signalling, are discussed.
Key words: Anion channels, Arabidopsis thaliana, pH regulation, plant, plasma membrane