The G protein-gated atrial K+ channel is stimulated by three distinct GIα-subunits

Atsuko Yatani, Rafael Mattera, Juan Codina, Rolf Graf, Kouji Okabe, Elena Padrell, Ravi Iyengar, Arthur M. Brown, Lutz Birnbaumer

Research output: Contribution to journalArticlepeer-review

205 Scopus citations


The gunanine nucleotide-binding protein, Gi, which inhibits adenylyl cyclase, has recently been shown to have three subtypes of the α-subunit, termed Giα-1, Giα-2 and Giα-3. They share 87-94% amino-acid sequence homology1-10 and so are difficult to separate from one another. Among other functions11-14, purified preparations activate K+ channels15-21 but there is confusion over which of the subtypes activates the muscarinic K+ channels of the atrial muscle of the heart: Giα-3, also termed Gk15, has been shown to activate this channel but it is not clear whether Giα-122 does21 or does not23,24. To clarify this problem, we expressed the subtypes separately in Escherichia coli to eliminate contamination by other subtypes and tested the recombinant α- chains on atrial muscarinic K+ channels. Although we anticipated that only Giα-3 would have Gctivity, to our surprise all three recombinant subtypes were active, from which we deduce that the Gi subtypes are multifunctional.

Original languageEnglish
Pages (from-to)680-682
Number of pages3
Issue number6200
StatePublished - 1988


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