GIRK Channel Trafficking: Different Paths for Different Family Members

Abstract

Ma et al. have reported that different G protein-regulated inwardly rectifying K⁺ (GIRK) channels composed of combinations of Kir3.1-Kir3.2-Kir3.3-Kir3.4 are localized to different subcellular compartments. Kir3.3 seems to target Kir3.1-containing channels to lysosomes, whereas Kir3.1-containing channels also consisting of Kir3.2 or Kir3.4 are successfully expressed at the cell surface. The new results suggest a mechanism whereby the surface expression of heterotetramers is controlled and thus channel density can be properly maintained. Mirshahi and Logothetis discuss the results and their implications for channel trafficking, but caution that we are far from understanding the whole regulatory process and that, indeed, other mechanisms participate in maintaining channel density.