Referenced in: none

Automatically associated channels: Kir2.1

Title: The role of a single aspartate residue in ionic selectivity and block of a murine inward rectifier K+ channel Kir2.1.

Authors: C J Abrams, N W Davies, P A Shelton, P R Stanfield

Journal, date & volume: J. Physiol. (Lond.), 1996 Jun 15 , 493 ( Pt 3), 643-9

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/8799888

Abstract
1. The effects of Rb+ and Cs+ as blocking ions were investigated on wild-type and mutant forms of the inward rectifier K+ channel, IRK1 (Kir2.1). 2. In wild-type channels, Rb+ blockage was voltage dependent, increasing and then falling with increasing hyperpolarization. 3. Rb+ blockage was abolished by replacing Asp172 in the M2 domain of the pore-forming subunit by Asn, but was re-established by a change to Gln, narrowing the pore. Blocking affinity was reduced in D172Q, and was also reduced by replacing Gly168 in M2 by Ala. 4. Cs+ blockage was also abolished in D172N but was re-established in D172Q. 5. There appears to be a balance between charge and pore size in determining whether ions block or permeate. A major part of the selectivity of Kir2.1 is associated with Asp172 in the M2 domain.