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A structural determinant of differential sensitivity of cloned inward rectifier K + channels to intracellular spermine
Author(s) -
Fakler B.,
Brändle U.,
Bond Ch.,
Glowatzki E.,
König C.,
Adelman J.P.,
Zenner H.-P.,
Ruppersberg J.P.
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)01258-x
Subject(s) - spermine , inward rectifier potassium ion channel , gating , biophysics , chemistry , intracellular , transmembrane domain , patch clamp , transmembrane protein , amino acid , ion channel , biochemistry , stereochemistry , biology , enzyme , receptor
Large subtype‐specific differences in the sensitivity of cloned inward‐rectifier K + channels of the IRK1, BIR10 and ROMK1 subtype to being blocked by intracellular spermine (SPM) are described. It is shown, by site‐directed mutagenesis, that the four orders of magnitude larger SPM sensitivity of BIR10 channels compared to ROMK1 channels may be explained by a difference in a single amino acid in the putative transmembrane segment TMII. This residue, a negatively charged glutamate in BIR10, is homologous to the residue in IRK1 and ROMK1 which has previously been shown to change gating properties and Mg 2+ sensitivity. Differential block by physiological SPM concentrations is suggested as a major functional difference between subtypes of inward‐rectifier K + channels.