Key result
This perspective discusses the thermodynamics of ion selectivity in the KcsA K+ channel, exploring how the protein selectively allows K+ flow over Na+ despite similar atomic radii.
Discusses the thermodynamic basis for the high selectivity of K+ over Na+ in voltage-gated K+ channels.
Thermodynamic models refine K+ selectivity understanding; extends channel biophysics but leaves clinical arrhythmia applications open.
In the voltage-gated K+ channels, measurements of ion channel permeability show that the protein selectively allows the flow of K+ over Na+ with a fidelity of better than 1 part in 1,000 (Latorre and Miller, 1983). Recent measurements (Lockless et al., 2007) of equilibrium selectivity also suggest that, relative to K+, Na+ hardly binds to the selectivity filter. These observations are striking given that the Pauling radius of K+ is only ~0.4 Å greater than that of Na+. Here, we provide our perspective on the thermodynamics of this selectivity.
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Dixit et al. (2011) reported a review. This perspective discusses the thermodynamics of ion selectivity in the KcsA K+ channel, exploring how the protein selectively allows K+ flow over Na+ despite similar atomic radii.
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