Figure 2

Representative photomicrographs illustrating fluorescence analysis and internalization of SSTR2 and SSTR3 upon agonist treatment. Cotransfected cells were treated with SST (1 μM), L-779976 (10 nM) and L-796778 (25 nM) for 15 min at 37°C, and processed for immunocytochemistry as described in Materials and methods. Fluorescent microscopic images show distribution of SSTR2 (red), SSTR3 (green) and colocalization (yellow) at the cell surface and intracellularly. SSTR2 and SSTR3 display colocalization at the cell surface and internalize upon treatment with SST and specific agonists. Note that activation of one receptor caused a significant down-regulation of both receptors at cell surface. Arrows and arrowheads in the merged panel represent membrane and cytosolic expression, respectively. Scale bar = 10 μm. Data are representative of mean ± S.D of three independent experiments.