GIRK channels are homo- and heterotetrameric complexes formed by 4 subunits (GIRK1/Kir3.1, GIRK2/Kir3.2, GIRK3/Kir3.3, and GIRK4/Kir3.4)2. While GIRK1, GIRK2, and GIRK3 are widely expressed in the brain7, GIRK4 is found in only a few brain regions8, 9. Most, if not all, neuronal GIRK channels contain GIRK24. Indeed, Girk2 −/− mice exhibit small or absent synaptic and somato-dendritic GIRK currents in all neuron types evaluated to date10–18. GIRK1 cannot form functional homomeric channels, as it lacks an endoplasmic reticulum export signal19–22, and is thought to assemble with GIRK2 in most brain regions23, 24. Thus, the prototypical GIRK channel in the central nervous system is thought to contain both GIRK1 and GIRK2.
