Recombinant G-protein βγ-subunits activate the muscarinic-gated atrial potassium channel

Kevin D. Wickman, Jorge A. Iñiguez-Lluhi, Philip A. Davenport, Ronald Taussig, Grigory B. Krapivinsky, Maurine E. Linder, Alfred G. Gilmant, David E. Clapham

Research output: Contribution to journalArticlepeer-review

382 Scopus citations


ACETYLCHOLINE activates inwardly rectifying potassium channels (I k.ACh) in the heart1 through muscarinic receptor binding and activation of pertussis-toxin-sensitive G proteins2,3. Experiments showing that only the βγ-subunit (Gβγ) activates IK.ACH(ref. 4) were challenged by reports that only the activated α-subunit (Gα) was effective5. Here we examine IK.ACh regulation using purified brain and recombinant G-protein subunits. Six recombinant Gβγ-subunits activated IK.ACh with apparent half-maximal activation concentrations of 3-30 nM. Activation of IK.ACh by recombinant Gα-GTPγS was observed, but this was probably due to release of GTPγS from the protein. Importantly, I K.ACh activity elicited by GTPγS was inhibited by purified brain and recombinant Gα-GDP, suggesting that native Gβγ plays a major role in this pathway. We conclude that Gβγ is a primary regulator of IK.ACh activity.

Original languageEnglish (US)
Pages (from-to)255-257
Number of pages3
Issue number6468
StatePublished - Jan 1 1994

ASJC Scopus subject areas

  • General


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