Cloning of a Xenopus laevis inwardly rectifying K+ channel subunit that permits GIRK1 expression of IKACh currents in oocytes

Neuron. 1996 Feb;16(2):423-9. doi: 10.1016/s0896-6273(00)80060-4.


Xenopus oocytes injected with GIRK1 mRNA express inwardly rectifying K+ channels resembling IKACh. Yet IKACh, the atrial G protein-regulated ion channel, is a heteromultimer of GIRK1 and CIR. Reasoning that an oocyte protein might be substituting for CIR, we cloned XIR, a CIR homolog endogenously expressed by Xenopus oocytes. Coinjecting XIR and GIRK1 mRNAs produced large, inwardly rectifying K+ currents responsive to m2-muscarinic receptor stimulation. The m2-stimulated currents of oocytes expressing GIRK1 alone decreased 80% after injecting antisense oligonucleotides specific to the 5' untranslated region of XIR, but GIRK1/CIR currents were unaffected. Thus, GIRK1 without XIR or CIR only ineffectively produces currents in oocytes. This result suggests that GIRK1 does not form native homomultimeric channels.

Publication types

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

MeSH terms

  • Acetylcholine / physiology
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cloning, Molecular*
  • Electric Conductivity
  • Female
  • G Protein-Coupled Inwardly-Rectifying Potassium Channels
  • Molecular Sequence Data
  • Oligonucleotides, Antisense / pharmacology
  • Oocytes / metabolism*
  • Potassium Channels / drug effects
  • Potassium Channels / genetics*
  • Potassium Channels / metabolism*
  • Potassium Channels / physiology*
  • Potassium Channels, Inwardly Rectifying*
  • Sequence Homology
  • Xenopus laevis / metabolism*


  • G Protein-Coupled Inwardly-Rectifying Potassium Channels
  • Oligonucleotides, Antisense
  • Potassium Channels
  • Potassium Channels, Inwardly Rectifying
  • Acetylcholine

Associated data

  • GENBANK/U42207