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

Stephen J. Tucker, Mauro Pessia, John Adelman

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

Coexpression in Xenopus oocytes of the cloned cardiac inward rectifier subunits Kir 3.1 and Kir 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, Kir 3.1 and Kir 3.4 were coexpressed 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 Kir 3.1, Kir 3.4, or the G protein-insensitive subunit Kir 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 (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume40
Issue number1
StatePublished - Jul 1996

Fingerprint

Muscarine
GTP-Binding Proteins
Inwardly Rectifying Potassium Channel
Protein Subunits
Xenopus
Muscle Cells
Cholinergic Agents
Oocytes

Keywords

  • Cloned subunits
  • G protein sensitivity
  • Muscarinic channel
  • Stoichiometry

ASJC Scopus subject areas

  • Physiology

Cite this

Muscarine-gated K+ channel : Subunit stoichiometry and structural domains essential for G protein stimulation. / Tucker, Stephen J.; Pessia, Mauro; Adelman, John.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 40, No. 1, 07.1996.

Research output: Contribution to journalArticle

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