The role of a single aspartate residue in ionic selectivity and block of a murine inward rectifier K+ channel Kir2.1.
AUTOR(ES)
Abrams, C J
RESUMO
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.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1159014Documentos Relacionados
- Characterization of the chicken inward rectifier K+ channel IRK1/Kir2.1 gene
- Flexibility of the Kir6.2 inward rectifier K+ channel pore
- [K+] dependence of open-channel conductance in cloned inward rectifier potassium channels (IRK1, Kir2.1).
- C-terminus determinants for Mg2+ and polyamine block of the inward rectifier K+ channel IRK1.
- Scanning mutagenesis of the putative transmembrane segments of Kir2.1, an inward rectifier potassium channel