SUBUNIT STOICHIOMETRY OF A HETEROMULTIMERIC G-PROTEIN-COUPLED INWARD-RECTIFIER K+ CHANNEL

We investigated the stoichiometry of the heteromultimeric G protein-co upled inward-recitfier K+ channel (GIRK) formed from GIRK1 and GIRK4 s ubunits. Multimeric GIRK constructs with several concatenated channel subunits were expressed in Xenopus oocytes. Coexpression of various tr imeric constructs with different monomers clearly showed that the func tional chan nel has stoichiometry (GIRK1)(2)(GIRK4)(2). Efforts to est ablish a preferred arrangement of subunits around the channel pore sug gest that more than one arrangement may be viable.