Shaking stack model of ion conduction through the Ca(2+)-activated K+ channel.
Motivated by the results of Neyton and Miller (1988. J. Gen. Physiol. 92:549-586), suggesting that the Ca(2+)-activated K+ channel has four high affinity ion binding sites, we propose a physically attractive variant of the single-vacancy conduction mechanism for this channel. Simple analytical expressions for conductance, current, flux ratio exponent, and reversal potential under bi-ionic conditions are found. A set of conductance data are analyzed to determine a realistic range of parameter values. Using these, we find qualitative agreement with a variety of experimental results previously reported in the literature. The exquisite selectivity of the Ca(2+)-activated K+ channel may be explained as a consequence of the concerted motion of the "stack" in the proposed mechanism.
Schumaker
M F
MF
Department of Pure and Applied Mathematics, Washington State University, Pullman 99164-3113.
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D004553:Electric Conductivity; D007700:Kinetics; D008051:Lipid Bilayers; D008433:Mathematics; D008564:Membrane Potentials; D008954:Models, Biological; D009132:Muscles / Q000502:physiology; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D051381:Rats
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