Referenced in: none

Automatically associated channels: Kv1.3 , Kv3.1

Title: The P-region and S6 of Kv3.1 contribute to the formation of the ion conduction pathway.

Authors: J Aiyar, A N Nguyen, K G Chandy, S Grissmer

Journal, date & volume: Biophys. J., 1994 Dec , 67, 2261-4

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/7696467

Abstract
The loop between transmembrane regions S5 and S6 (P-region) of voltage-gated K+ channels has been proposed to form the ion-conducting pore, and the internal part of this segment is reported to be responsible for ion permeation and internal tetraethylammonium (TEA) binding. The two T-cell K+ channels, Kv3.1 and Kv1.3, with widely divergent pore properties, differ by a single residue in this internal P-region, leucine 401 in Kv3.1 corresponding to valine 398 in Kv1.3. The L401V mutation in Kv3.1 was created with the anticipation that the mutant channel would exhibit Kv1.3-like deep-pore properties. Surprisingly, this mutation did not alter single channel conductance and only moderately enhanced internal TEA sensitivity, indicating that residues outside the P-region influence these properties. Our search for additional residues was guided by the model of Durell and Guy, which predicted that the C-terminal end of S6 formed part of the K+ conduction pathway. In this segment, the two channels diverge at only one position, Kv3.1 containing M430 in place of leucine in Kv1.3. The M430L mutant of Kv3.1 exhibited permeant ion- and voltage-dependent flickery outward single channel currents, with no obvious changes in other pore properties. Modification of one or more ion-binding sites located in the electric field and possibly within the channel pore could give rise to this type of channel flicker.