Patch clamp analysis of the dominant plasma membrane K+ channel in root cell protoplasts of Plantago media L. Its significance for the P and K state.
Ion channels in the plasma membrane of root cell protoplasts of Plantago media L. were studied with the patch clamp technique in the cell-attached patch and outside-out patch configuration. An outward rectifying potassium channel was dominantly present in the plasma membrane. It appears responsible for the diffusional part, dominated by the K+ diffusion potential, of the cell membrane potential, in vivo. This channel is activated at potentials near to and more positive than the K+ diffusion potential. The dependence of this ion channel on K+ activity and voltage has been characterized. The current-voltage relationships of the open channel at various K+ concentrations are described by a four-state model. The membrane potential of intact protoplasts appears either dominated by the K+ diffusion potential, the protoplast is then said to be in the K state, or by the pump potential generated by the plasma membrane-bound proton pump/H+ ATPase, the P state. An experimental procedure is described to determine in cell-attached patch mode the state of the protoplast, either K or P state.
Vogelzang
S A
SA
Department of Plant Biology, Biological Center, University of Groningen, Haren, The Netherlands.
Prins
H B
HB
D002462:Cell Membrane / Q000502:physiology; D004058:Diffusion; D004553:Electric Conductivity; D004594:Electrophysiology / Q000379:methods; D007700:Kinetics; D008564:Membrane Potentials; D008954:Models, Biological; D008962:Models, Theoretical; D018517:Plant Roots; D010943:Plantago; D010946:Plants, Medicinal; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000502:physiology*; D006180:Proton-Translocating ATPases / Q000378:metabolism; D011523:Protoplasts / Q000502:physiology*
D015221:Potassium Channels; D006180:Proton-Translocating ATPases; D011188:Potassium