Multiple residues specify external tetraethylammonium blockade in voltage-gated potassium channels

J. M. Pascual, C. C. Shieh, G. E. Kirsch, A. M. Brown

Research output: Contribution to journalArticle

44 Scopus citations

Abstract

We have mapped residues in the carboxyl half of the P region of a voltage-gated K+ channel that influence external tetraethylammonium (TEA) block. Fifteen amino acids were substituted with cysteine and expressed in oocytes from monomeric or heterodimeric cRNAs. From a total of six mutant channels with altered TEA sensitivity, three were susceptible to modification by extracellularly applied charged methanethiosulfonates (MTSX). Another residue did not affect TEA block but was protected from MTSX by TEA. MTSX modification of position Y380C, thought to form the TEA binding site, affected TEA affinity only moderately, and this effect could be reversed by additional charge transfer from an oppositely charged MTSX analog. The results show that TEA block is modulated from multiple sites, including residues located deep in the pore and that several side chains besides that of Y380 are exposed at the TEA receptor.

Original languageEnglish (US)
Pages (from-to)428-434
Number of pages7
JournalBiophysical journal
Volume69
Issue number2
DOIs
StatePublished - Jan 1 1995

ASJC Scopus subject areas

  • Biophysics

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