Differential contribution by conserved glutamate residues to an ion-selectivity site in the L-type Ca2+ channel pore

Gabor Mikala, Anthony Bahinski, Atsuko Yatani, Shaoqing Tang, Arnold Schwartz

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Abstract

In voltage-gated cation channels, it is thought that residues responsible for ion-selectivity are located within the pore-lining SS1-SS2 segments. In this study, we compared the ion permeation properties of mutant calcium channels in which highly conserved glutamate residues, located at analogous positions in the SS2 regions of all four motifs, were individually replaced. All of the mutants exhibited a loss of selectivity for divalent over monovalent cations. However, the permeation properties of the individual mutants varied in a position dependent manner. The results provide strong evidence that these glutamate residues, positioned at equivalent locations in the aligned sequences, play significantly different roles in forming the selectivity barrier of the calcium channel, and are probably arranged in an asymmetrical manner inside the ion-conducting pore.

Original languageEnglish
Pages (from-to)265-269
Number of pages5
JournalFEBS letters
Volume335
Issue number2
DOIs
Publication statusPublished - Dec 6 1993

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Keywords

  • Calcium channel
  • Ion permeation
  • Pore structure
  • SS1-SS2 region
  • Site-directed mutagenesis

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

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