Ion channels and ion selectivity

Ion conduction and selectivity in K(+) channels.

Potassium (K(+)) channels are tetrameric membrane-spanning proteins that provide a selective pore for the conductance of K(+) across the cell membranes. These channels are most remarkable in their ability to discriminate K(+) from Na(+) by more than a thousandfold and conduct at a throughput rate near diffusion limit. The recent progress in the structural characterization of K(+) channel provid...

Ion Conduction and Selectivity in K+ Channels

Ion selectivity in channels and transporters

A multitude of biological processes requires the participation of specific cations, such as H + , Na + , K + , Ca 2+ , and Mg 2+. Many of these processes can take place only when proteins have the ability to discriminate between different ions with a very high fidelity. How this is possible is a fundamental question that has fascinated scientists for a long time. At the most fundamental level, ...

Structure and selectivity in bestrophin ion channels.

Human bestrophin-1 (hBest1) is a calcium-activated chloride channel from the retinal pigment epithelium, where mutations are associated with vitelliform macular degeneration, or Best disease. We describe the structure of a bacterial homolog (KpBest) of hBest1 and functional characterizations of both channels. KpBest is a pentamer that forms a five-helix transmembrane pore, closed by three rings...

A physical mechanism for large-ion selectivity of ion channels

a Department of Physiology and Biophysics, University of Miami School of Medicine, P. O. Box 016430, Miami, FL 33101, USA. E-mail: [email protected]; [email protected] b Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 86402-5700, USA. E-mail: [email protected] c Department of Molecular Biophysics and Physiology, Rush Medical College, 1750 W. Har...