FIGURE 1.

Homomeric complexes of SMSs are more stable than heteromeric ones. A and B, HEK293/SMS1-V5 cells (A) or HEK293/SMS2-V5 cells (B) were transfected with a plasmid encoding FLAG-tagged SMS1 or FLAG-tagged SMS2 or mock-transfected (empty vector). The cells were lysed in a buffer containing 1% Triton X-100, and immunoprecipitation (IP) was performed using anti-FLAG M2 beads. The cell lysates, supernatant (sup), and precipitated proteins were analyzed by immunoblotting (IB) with anti-FLAG or anti-V5 antibody. Left, cell lysate; center, supernatant; right, immunoprecipitates (anti-FLAG beads). C, membrane fractions from COS7 cells expressing V5-tagged SMS1, SMS2, or aquaporin-1 were extracted with 1% Triton X-100, separated by BN-PAGE, and immunoblotted with anti-V5 antibody. H, major band of high molecular mass; L, minor band of low molecular mass. NativeMark unstained protein standard was used for molecular mass estimation. Results are from one experiment representative of three independent experiments.