title: Distinct pH regulation of slow and rapid anion channels at the plasma membrane of Arabidopsis thaliana hypocotyl cells.
abstract: 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.
authors.affiliation: Institut des Sciences du Végétal, CNRS UPR 2355, F-91198 Gif sur Yvette, France. jcolcomb@biomail.ucsd.edu
authors.forename: Jean
authors.initials: J
authors.lastname: Colcombet
authors.forename: Françoise
authors.initials: F
authors.lastname: Lelièvre
authors.forename: Sébastien
authors.initials: S
authors.lastname: Thomine
authors.forename: Hélène
authors.initials: H
authors.lastname: Barbier-Brygoo
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Frachisse
mesh_terms: D000838:Anions / Q000378:metabolism*; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D018546:Hypocotyl / Q000378:metabolism; D007473:Ion Channels / Q000378:metabolism*; D008564:Membrane Potentials
chemical_list: D000838:Anions; D029681:Arabidopsis Proteins; D007473:Ion Channels