학술논문
Stable cation coordination at a single outer pore residue defines permeation properties in Kir channels
Document Type
Article
Source
FEBS Letters; January 2000, Vol. 466 Issue: 1 p115-120, 6p
Subject
Language
ISSN
00145793
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 Xenopusoocytes was Tl+>K+>Rb+>NH4+>Cs+>Na+>Li+, but the macroscopic conductance for Rb+was ∼8‐fold larger than for the smaller K+ions, and decreased ∼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.