Stable cation coordination at a single outer pore residue defines permeation properties in Kir channels |
| |
Authors: | Wischmeyer E Döring F Karschin A |
| |
Institution: | Department of Molecular Neurobiology of Signal Transduction, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, 37070, G?ttingen, Germany. |
| |
Abstract: | In epithelial Kir7.1 channels a non-conserved methionine in the outer pore region adjacent to the G-Y-G selectivity filter (position +2) was found to determine unique properties for permeant and blocking ions characteristic of a K(+) channel in a single-occupancy state. The monovalent cation permeability sequence of Kir7.1 channels expressed in Xenopus oocytes was Tl(+)>K(+)>Rb(+)NH(4)(+)>Cs(+)>Na(+)>Li(+), but the macroscopic conductance for Rb(+) was approximately 8-fold larger than for the smaller K(+) ions, and decreased approximately 40-fold with the conserved arginine at the +2 position (Kir7.1M125R). Moreover, in Kir7.1 Rb(+) restored the typical permeation properties of other multi-ion channels indicating that a stable coordination of permeant ions at the +2 position defines the initial step in the conduction pathway of Kir channels. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|