Fig. 1.

Sulfonylurea receptor (SUR) 2 targets inwardly rectifying K⁺ (Kir) 6.1 and Kir6.2 to intracellular vesicles. COS-1L cells were transfected with plasmids encoding Kir6.1myc (top) or Kir6.2-hemagglutinin (HA) (middle) together with SUR1 or SUR2A or in the absence of SURx (with pcDNA3). Cells were pretreated with cycloheximide for 4 h before staining for immunofluorescence microscopy (IFM). When expressed alone, Kir6.1 or Kir6.2 staining was in a reticular pattern consistent with retention in the endoplasmic reticulum. When expressed together with SUR1, both Kir6.1 and Kir6.2 were predominantly localized on plasma membranes (arrowheads). When expressed with SUR2, both Kir6.1 and Kir6.2 were detected in intracellular vesicles (arrows) and on the plasma membrane. Bottom: COS-1L cells were transfected with a 1:9 (left) or a 1:1 (right) ratio of Kir6.1:SUR2B plasmid DNA and stained for IFM using goat anti-Kir6.1 or SUR2B antibodies. The untagged Kir6.1 subunit was localized to intracellular vesicles (arrows). SUR2B was also localized to intracellular vesicles. Figure panels have been adjusted for brightness and contrast. Bars = 10 μm.