Figure 1.

Alanine scanning mutagenesis of COOH-terminal basic residues. (A) Primary sequence of Kir6.2, highlighted to show transmembrane M1 and M2 domains together with the P-loop (gray), and regions that enclose PIP₂-sensitive residues (pink). All residues that were mutated in this study are indicated (bold), including those that alter PIP₂ response in this study (red) or ATP sensitivity (blue). Also indicated are the PIP₂-sensitive residues identified in Kir2.1/Kir3.1 by Zhang et al. 1999(orange). (B) ⁸⁶Rb efflux in 40 min from COSm6 cells cotransfected with mutant Kir6.2 subunits (as indicated) + SUR1, expressed as a percentage of the efflux from cotransfected wild-type Kir6.2 + SUR1 subunits in parallel transfections (mean ± SEM, n = 3 in each case). See materials and methods for details.