Molecular cloning and functional expression of a novel brain-specific inward rectifier potassium channel

FEBS Lett. 1994 Jun 13;346(2-3):251-6. doi: 10.1016/0014-5793(94)00483-8.


We have cloned a novel brain-specific inward rectifier K+ channel from a mouse brain cDNA library and designated it MB-IRK3. The mouse brain cDNA library was screened using a fragment of the mouse macrophage inward rectifier K+ channel (IRK1) cDNA as a probe. The amino acid sequence of MB-IRK3 shares 61% and 64% identity to MB-IRK1 and RB-IRK2, respectively. Xenopus oocytes injected with cRNA derived from this clone expressed a potassium current which showed inward-rectifying channel characteristics similar to MB-IRK1 and RB-IRK2 currents, but distinct from ROMK1 or GIRK1 current. However, the single channel conductance of MB-IRK3 was approximately 10 pS with 140 mM extracellular K+, which was distinct from that of MB-IRK1 (20 pS). MB-IRK3 mRNA expressed specifically in the forebrain, which clearly differed from MB-IRK1 and RB-IRK2 mRNAs. These results indicate that members of the IRK family with distinct electrophysiological properties express differentially and may play heterogenous functional roles in brain functions.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Barium / pharmacology
  • Base Sequence
  • Brain Chemistry*
  • Cloning, Molecular*
  • Electric Conductivity
  • Electrophysiology
  • Female
  • Gene Expression*
  • Gene Transfer Techniques
  • Membrane Potentials
  • Mice
  • Molecular Sequence Data
  • Oocytes / metabolism
  • Potassium Channels / chemistry
  • Potassium Channels / genetics*
  • Potassium Channels / physiology
  • Potassium Channels, Inwardly Rectifying*
  • RNA, Messenger / analysis
  • Tissue Distribution
  • Xenopus


  • Potassium Channels
  • Potassium Channels, Inwardly Rectifying
  • RNA, Messenger
  • Barium

Associated data

  • GENBANK/S71382