Muscarine-gated K+ channel: Subunit stoichiometry and structural domains essential for G protein stimulation

Stephen J. Tucker, Maueo Pessia, John P. Adelman

Research output: Contribution to journalArticlepeer-review

46 Citations (Scopus)


Coexpression in Xenopus oocytes of the cloned cardiac inward rectifier subunits K(ir) 3.1 and K(ir) 3,4 results in G protein-stimulated channel activity closely resembling the muscarinic channel underlying the inwardly rectifying K+ current in atrial myocytes. To determine the stoichiometry and relative subunit positions within the channel, K(ir). 3.1 and K(ir) 3.4 were eoexpressed in varying ratios with cloned Gβ1γ2 subunits and also as tandemly linked tetramers with different relative subunit positions. The results reveal that the most efficient channel comprises two subunits of each type in an alternating array within the tetramer. To localize regions important for subunit coassembly and G protein sensitivity, chimeric subunits containing domains from either K(ir) 3.1, K(ir) 3.4, or the G protein- insensitive subunit K(ir) 4.1 were expressed. The results demonstrate that the transmembrane domains dictate the potentiation of the coassembled channels and that, although the NH4- or COOH-termini of both subunits alone can confer G protein sensitivity, both termini are required for maximal stimulation by Gβ1γ2.

Original languageEnglish
Pages (from-to)H379-H385
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number1 40-1
Publication statusPublished - Jul 1996
Externally publishedYes


  • G protein sensitivity
  • cloned subunits
  • muscarinic channel
  • stoichiometry

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)


Dive into the research topics of 'Muscarine-gated K+ channel: Subunit stoichiometry and structural domains essential for G protein stimulation'. Together they form a unique fingerprint.

Cite this