Summary
Voltage-dependent K channels could be identified in on-cell and excised patch-clamp records on membranes of isolated plant cell vacuoles. The current through a membrane patch is dominated by a channel population with a conductance of about 121 pS in symmetrical 250mm KCl solution. The single channel adopts at least two conducting levels the 121-pS state being most frequently observed. The channel shows outward rectification, representing a cation flux into the vacuoles. The rectification appears to be caused by a vanishing open probability and a short channel lifetime at hyperpolarizing voltages. A selectivity ratio of potassium over sodium of about 6 was derived as an estimate. Occasionally, an additional population of K channels with a single-channel conductance of approximately 18 pS is observed. This channel type exhibits outward rectification as well.
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Kolb, H.A., Köhler, K. & Martinoia, E. Single potassium channels in membranes of isolated mesophyll barley vacuoles. J. Membrain Biol. 95, 163–169 (1987). https://doi.org/10.1007/BF01869161
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DOI: https://doi.org/10.1007/BF01869161