Click here to close Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly. We suggest using a current version of Chrome, FireFox, or Safari.
XB-ART-34787
Proc Natl Acad Sci U S A 2006 Sep 26;10339:14355-60. doi: 10.1073/pnas.0606660103.
Show Gene links Show Anatomy links

Electrostatic interactions in the channel cavity as an important determinant of potassium channel selectivity.

Bichet D , Grabe M , Jan YN , Jan LY .


???displayArticle.abstract???
Potassium channels are membrane proteins that allow the passage of potassium ions at near diffusion rates while severely limiting the flux of the slightly smaller sodium ions. Although studies thus far have focused on the narrowest part of the channel, known as the selectivity filter, channels are long pores with multiple ions that traverse the selectivity filter, the water-filled central cavity, and the rest of the pore formed by cytoplasmic domains. Here, we present experimental analyses on Kir3.2 (GIRK2), a G protein-activated inwardly rectifying potassium (Kir) channel, showing that a negative charge introduced at a pore-facing position in the cavity (N184) below the selectivity filter restores both K(+) selectivity and inward rectification properties to the nonselective S177W mutant channel. Molecular modeling demonstrates that the negative residue has no effect on the geometry of the selectivity filter, suggesting that it has a local effect on the cavity ion. Moreover, restoration of selectivity does not depend on the exact location of the charge in the central cavity as long as this residue faces the pore, where it is in close contact with permeant ions. Our results indicate that interactions between permeant ions and the channel cavity can influence ion selectivity and channel block by means of an electrostatic effect.

???displayArticle.pubmedLink??? 16983069
???displayArticle.pmcLink??? PMC1570129
???displayArticle.link??? Proc Natl Acad Sci U S A
???displayArticle.grants??? [+]

Species referenced: Xenopus laevis
Genes referenced: kcnj6

References [+] :
Bhattacharjee, Slick (Slo2.1), a rapidly-gating sodium-activated potassium channel inhibited by ATP. 2003, Pubmed, Xenbase