Referenced in: none

Automatically associated channels: Kir2.1 , Kir3.1

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

Authors: K E Hedin, N F Lim, D E Clapham

Journal, date & volume: Neuron, 1996 Feb , 16, 423-9

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/8789957

Abstract
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.