Magnesium-independent activation of inward-rectifying K+ channels in Vicia faba guard cells.
The activation of inward-rectifying K+ channels in guard cells at membrane potentials negative of the K+ equilibrium potential is important for their cellular function as proton pump-driven K+ uptake pathways during stomatal opening. In animal cells the voltage-dependence of inward-rectifying K+ channels is produced to a large extent by intracellular magnesium block. In guard cells, when cytosolic Mg2+ was either 3 mM or < 1 microM, activation times, deactivation times and the steady-state voltage-dependence of K+ channels remained unchanged. It is discussed that the activation mechanism of inward-rectifying K+ channels in guard cells is independent of intracellular Mg2+ block.
Schroeder
J I
JI
Department of Biology, University of California at San Diego, La Jolla 92093-0116, USA.
D002118:Calcium / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D004492:Edetic Acid / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004553:Electric Conductivity; D007887:Fabaceae; D008274:Magnesium / Q000378:metabolism / Q000494:pharmacology*; D008564:Membrane Potentials; D018408:Patch-Clamp Techniques; D010946:Plants, Medicinal; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*
D015221:Potassium Channels; D004533:Egtazic Acid; D004492:Edetic Acid; D008274:Magnesium; D002118:Calcium