pH control of the plant outwardly-rectifying potassium channel SKOR.
SKOR, an Arabidopsis depolarisation-activated K+-selective channel, was expressed in Xenopus oocytes, and external and internal pH effects were analysed. Internal pH was manipulated by injections of alkaline or acidic solutions or by acid load from acetate-containing medium. An internal pH decrease from 7.4 to 7.2 induced a strong (ca. 80%) voltage-independent decrease of the macroscopic SKOR current, the macroscopic gating parameters and the single channel conductance remained unchanged. An external acidification from 7.4 to 6.4 had similar effects. It is proposed that pH changes regulate the number of channels available for activation. Sensitivity of SKOR activity to pH in the physiological range suggests that internal and external pH play a role in the regulation of K+ secretion into the xylem sap.
Lacombe
B
B
Biochimie et Physiologie Moléculaire des Plantes, Montpellier, France.
Pilot
G
G
Gaymard
F
F
Sentenac
H
H
Thibaud
J B
JB
D000818:Animals; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins; D006863:Hydrogen-Ion Concentration; D007473:Ion Channels / Q000378:metabolism / Q000502:physiology; D008564:Membrane Potentials; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000378:metabolism*; D051637:Shaker Superfamily of Potassium Channels; D014981:Xenopus
D029681:Arabidopsis Proteins; D007473:Ion Channels; D015221:Potassium Channels; C114544:SKOR protein, Arabidopsis; D051637:Shaker Superfamily of Potassium Channels