SHERP

Multiple Residues in the P-Region and M2 of Murine Kir 2.1 Regulate Blockage by External Ba(2+)

Cited 0 time in webofscience Cited 0 time in scopus
Authors
Lee, Young Mee; Thompson, Gareth A.; Leyland, Mark; Ashmole, Ian; So, Insuk; Stanfield, Peter R.
Issue Date
2009-02
Publisher
KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY
Citation
KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY; Vol.13 1; 61-70
Keywords
Potassium channelInward rectifierIonic selectivityBarium blockage
Abstract
We have examined the effects of certain mutations of the selectivity filter and of the membrane helix M2 on Ba(2+) blockage of the inward rectifier potassium channel, Kir 2.1. We expressed mutant and wild type murine Kir 2.1 in Chinese hamster ovary (CHO) cells and used the whole cell patch-clamp technique to record K(+) currents in the absence and presence of externally applied Ba(2+). Wild type Kir2.1 was blocked by externally applied Ba2+ in a voltage and concentration dependent manner. Mutants of Y145 in the selectivity filter showed little change in the kinetics of Ba2+ blockage. The estimated K(d)(0) was 108 mu M for Kir2.1 wild type, 124 mu M for a concatameric WT-Y145V dimer, 109 mu M for a WT-Y145L dimer, and 267 mu M for Y145F. Mutant channels T141A and S165L exhibit a reduced affinity together with a large reduction in the rate of blockage. In S165L, blockage proceeds with a double exponential time course, suggestive of more than one blocking site. The double mutation T141A/S165L dramatically reduced affinity for Ba(2+), also showing two components with very different time courses. Mutants D172K and D172R (lining the central, aqueous cavity of the channel) showed both a decreased affinity to Ba(2+) and a decrease in the on transition rate constant (k(on)). These results imply that residues stabilising the cytoplasmic end of the selectivity filter (T141, S165) and in the central cavity (D172) are major determinants of high affinity Ba(2+) blockage in Kir 2.1.
ISSN
1226-4512
Language
English
URI
http://hdl.handle.net/10371/77360
Files in This Item:
Appears in Collections:
College of Medicine/School of Medicine (의과대학/대학원)Dept. of Physiology (생리학교실)Journal Papers (저널논문_생리학교실)
  • mendeley

Items in S-Space are protected by copyright, with all rights reserved, unless otherwise indicated.

Browse