Fig. 7. Impairing 14-3-3 recruitment to the K_ATP-channel complex results in reduced surface expression but does not alter K_ATP-channel function. (A) (Top) Surface expression in COS1 cells of SUR1-Kir6.2 proteins containing WT or mutated RKR motifs, and the RKR C10 variant of Kir6.2, as indicated. Data are the mean ± s.e.m. of at least nine dishes of cells in each case. Data are normalized to the values measured for the SUR1_RKR-Kir6.2_RKR construct. Data for SUR1_RKR-Kir6.2_RKR C10 were significantly different to SUR1_RKR-Kir6.2_RKR (P<0.0001) and SUR1_AAA-Kir6.2_RKR (P<0.001). (Bottom) Western blots of anti-HA immunoprecipitates from cell extracts probed with an anti-HA antibody, showing similar expression levels for the fusion proteins tested. (B) Mean ATP concentration-inhibition relationships for K_ATP channels. Data were obtained from HEK293 cells expressing recombinant WT channels (triangles), the SUR1-Kir6.2 fusion (circles) or SUR1-Kir6.2 C10 (squares). Black symbols, Mg²⁺-containing solution. White symbols, Mg²⁺-free solution. The curves are the best fit of the Hill equation to the mean data, with IC₅₀=20 µM, h=0.8 (, n=6), IC₅₀=389 µM, h=0.8 (, n=6), IC₅₀=370 µM, h=0.7 (, n=6), IC₅₀=80 µM, h=0.9 (, n=6), and IC₅₀=107 µM, h=0.9 (, n=6).