REGIONS RESPONSIBLE FOR THE ASSEMBLY OF INWARDLY RECTIFYING POTASSIUMCHANNELS

Inwardly rectifying potassium channels have an important role in deter mining the resting potential of the cell. They are tetrameric proteins with two transmembrane segments (M1 and M2), a pore-forming loop (H5) , a cytoplasmic N-terminal, and longer C-terminal domain. We have used biochemical and electrophysiological methods to identify regions requ ired for homotypic interactions and those responsible for the incompat ibility between IRK1 and two other members of the same subfamily (IRK2 and IRK3) and two members from other subfamilies (ROMK1 and 6.1\uK(AT P)). The data indicate that, in contrast to the voltage-gated class of potassium channel, the proximal C-terminus and the transmembrane segm ent M2 determine homo- and heteromultimerization and that heteromultim erization between members of the same or different subfamilies is case specific.