Conserved and unique salt bridge interactions at the CD-I in Kir channels. (A) Sequence alignment of eukaryotic Kir channel residues in the cytoplasmic domain. Charged residues that form intersubunit CD-I interactions are highlighted and colored with respect to their subunit orientation. (B and C) Homology models of mouse Kir6.2 (mKir6.2; B) and human Kir2.1 (hKir2.1; C) with adjacent subunits individually colored (blue and green) and cartoon representation of intersubunit interactions (R192–E229 in mKir6.2 and R204–E241 and D205–R235 in hKir2.1).