Figure 5.

Phosphoinositide specificity of the C-terminal and combination Kir2.1 mutants. (A) Multiple sequence alignment of the cytoplasmic C terminus of Kir channels. Only segments containing residues that correlated with phosphoinositide specificity are shown for clarity. Blue residues correlated with specificity and red residues correlated with the lack of specificity. Putative PIP₂-interacting residues are green (see refs. 14 and 33). Numbers on the top correspond to positions of PIP₂-specificity-candidate residues in Kir2.1. The * denotes a mutant that was not activated by diC₈ phosphoinositides (H226S). (B) Phosphoinositide activation of individual mutants in the background of Kir2.1. Experiments were performed and data are displayed as in Fig. 3. (C) Phosphoinositide activation of combination mutants in the background of Kir2.1. Asterisks denote statistically significant differences from the wild-type Kir2.1. *, P < 0.05; ***, P < 0.001.