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Cell. 2002 Dec 27;111(7):957-65.

Structural basis of inward rectification: cytoplasmic pore of the G protein-gated inward rectifier GIRK1 at 1.8 A resolution.

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Howard Hughes Medical Institute and Laboratory of Molecular Neurobiology and Biophysics, Rockefeller University, New York, NY 10021, USA.


Inward rectifier K(+) channels govern the resting membrane voltage in many cells. Regulation of these ion channels via G protein-coupled receptor signaling underlies the control of heart rate and the actions of neurotransmitters in the central nervous system. We have determined the protein structure formed by the intracellular N- and C termini of the G protein-gated inward rectifier K(+) channel GIRK1 at 1.8 A resolution. A cytoplasmic pore, conserved among inward rectifier K(+) channels, extends the ion pathway to 60 A, nearly twice the length of a canonical transmembrane K(+) channel. The cytoplasmic pore is lined by acidic and hydrophobic amino acids, creating a favorable environment for polyamines, which block the pore. These results explain in structural and chemical terms the basis of inward rectification, and they also have implications for G protein regulation of GIRK channels.

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