A structural determinant of differential sensitivity of cloned inward rectifier K+ channels to intracellular spermine

B. Fakler, U. Brändle, Ch Bond, E. Glowatzki, C. König, J. P. Adelman, H. P. Zenner, J. P. Ruppersberg

Research output: Contribution to journalArticlepeer-review

129 Scopus citations


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 Mg2+ sensitivity. Differential block by physiological SPM concentrations is suggested as a major functional difference between subtypes of inward-rectifier K+ channels.

Original languageEnglish (US)
Pages (from-to)199-203
Number of pages5
JournalFEBS Letters
Issue number2-3
StatePublished - Dec 19 1994
Externally publishedYes


  • Clone
  • Inward rectifier
  • K channel
  • Site-directed mutagenesis
  • Spermine

ASJC Scopus subject areas

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


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