Figure 1. ⁸⁶Rb⁺ efflux from untransfected COSm6 cells and cells expressing truncated Kir6.2 subunits alone or with SUR1.

A, schematic diagram of the Kir6.2 subunit illustrating the regions in the cytoplasmic C- and N-termini that were deleted or mutated. The Kir6.2 subunit contains two transmembrane segments, M1 and M2, a pore-forming H5 segment, and cytoplasmic N- and C-termini. A lysine residue at position 185 has previously been implicated in inhibition of the K_ATP channel by ATP (Tucker et al. 1997). B, percentage efflux of ⁸⁶Rb⁺ as a function of time in the presence of metabolic inhibitors (see Methods) for wild-type Kir6.2 and N-terminal deletion constructs, with or without SUR1 as indicated. All transfections were done in parallel. Graph shows results from a typical experiment (repeated 2-3 times for each construct).