Inwardly Rectifying Potassium Channels

Inwardly rectifying potassium (Kir) channels exhibit little or no intrinsic voltage dependence, but their activity can be dramatically influenced by a number of ligands and naturally occurring channel blockers. Kir channels play a critical role in a number of physiological processes and genetic diseases, and recent structural descriptions of a bacterial Kir homolog and isolated domains of eukaryotic Kirs have contributed to our detailed understanding of the function and regulation of these channels. This article describes the critical structural features of Kir channels and the mechanisms underlying channel regulation by polyamine blockers and various ligands, including nucleotides, Gβγsubunits, and phospholipids.