Schematic representation of connected tetramers. Schematic representation of the six tetrameric constructs employed. The distribution of wild-type (WT) and mutant K185E subunits is shown, together with the connecting amino acids. The arginine-serine (RS) in the connecting regions is supplied by the fused BglII and BamHI sites used in cloning. Open circles, wild-type Kir6.2 subunits; filled circles, Kir6.2-K185E subunits.