Protons decrease the single channel conductance of the sarcoplasmic reticulum K+ channel in neutral and negatively charged bilayers.
The conductance of rabbit sarcoplasmic reticulum K+ channels incorporated into artificial bilayers of varying lipid composition was measured at different K+ and proton concentrations. Protons competitively inhibit the K+ conductance with a Ki of 0.5 microM. In negatively charged membranes, the conductance is well described by Gouy-Chapman-Stern theory modified to include the inhibitory effect of protons of the conductance and assuming that the channel mouth is isolated by 5-10 A from bilayer surface.
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D000818:Animals; D004553:Electric Conductivity; D006863:Hydrogen-Ion Concentration; D007473:Ion Channels / Q000502:physiology*; D007700:Kinetics; D008051:Lipid Bilayers; D011188:Potassium / Q000378:metabolism*; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000502:physiology*; D013816:Thermodynamics
D007473:Ion Channels; D008051:Lipid Bilayers; D011188:Potassium