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Review
. 2011 May;137(5):405-13.
doi: 10.1085/jgp.201010551.

Origins of ion selectivity in potassium channels from the perspective of channel block

Crina M Nimigean  1 , Toby W Allen
Affiliations
Review

Origins of ion selectivity in potassium channels from the perspective of channel block

Crina M Nimigean et al. J Gen Physiol. 2011 May.
No abstract available

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Figures

Figure 1.
Figure 1.
Structure of KcsA (Zhou et al., 2001) (deposited in the Protein Data Bank under accession no. 1K4C) with only two opposing subunits shown for clarity: the carbonyl oxygens forming the K+-binding sites in the selectivity filter (S0–S4) in red and K+ ions in purple.
Figure 2.
Figure 2.
Na+ blocks K+ current through KcsA with fast and slow kinetics. (A) Single-channel current recordings adapted from Thompson et al. (2009), illustrating the decrease in K+ current amplitude and the decrease in burst durations in the presence of intracellular Na+. (B) I-V curves from Nimigean and Miller (2002), showing the effect of Na+ on the K+ single-channel current amplitude (red). Control data (black) and ideal Woodhull (1973) block (dashed line). (C) Mean burst durations decrease with increasing Na+ and voltage. Adapted from Thompson et al. (2009).
Figure 3.
Figure 3.
Selectivity filter sites suggested by MD simulations (Kim and Allen, 2010). On the right is a hypothetical free energy profile where K+ and Na+ would have similar thermodynamic stabilities. Precise heights of the barriers are arbitrary in this cartoon.
Figure 4.
Figure 4.
KcsA selectivity filter conformations from x-ray crystallography experiments in the following conditions: (A) high K+ (Zhou et al., 2001) (deposited in the Protein Data Bank under accession no. 1K4C); (B) high Na+ and no K+ (Zhou et al., 2001) (Protein Data Bank accession no. 2ITC); (C) high Li+ and no K+ (Thompson et al., 2009) (Protein Data Bank accession no. 3GB7). (Inset) An increased representation of the S3 and S4 sites at the bottom of the selectivity filter where Li+ is proposed to bind, with the coordination distances indicated. Purple, K+ ions; red, waters; blue, Na+ ions; green, Li+ ions.
Figure 5.
Figure 5.
Origin of the multi-ion barrier for Na+ outward permeation in the presence of K+ ions. See text for description. Based on Thompson et al. (2009).
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References

    1. Adelman W.J., Jr, French R.J. 1978. Blocking of the squid axon potassium channel by external caesium ions. J. Physiol. 276:13–25 - PMC - PubMed
    1. Alberts B., Johnson A., Lewis J., Raff M., Roberts K., Walter P. 2007. Molecular Biology of the Cell. Fifth edition Garland Science, New York: 1392 pp
    1. Allen T.W., Chung S.H. 2001. Brownian dynamics study of an open-state KcsA potassium channel. Biochim. Biophys. Acta. 1515:83–91 10.1016/S0005-2736(01)00395-9 - DOI - PubMed
    1. Allen T.W., Hoyles M., Kuyucak S., Chung S.H. 1999. Molecular and Brownian dynamics study of ion selectivity and conductivity in the potassium channel. Chem. Phys. Lett. 313:358–365 10.1016/S0009-2614(99)01004-0 - DOI
    1. Allen T.W., Bliznyuk A., Rendell A.P., Kuyucak S., Chung S.H. 2000. The potassium channel: structure, selectivity and diffusion. J. Chem. Phys. 112:8191–8204 10.1063/1.481420 - DOI

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