Fig. 6. RAMP stimulates the traffic of the CaSR from the ER to the Golgi apparatus. Subcellular localisation of the SEP-CaSR in the ER and the Golgi apparatus in COS7 cells expressing the receptor in the absence (upper panels, a-h) or in the presence of RAMP (HA-RAMP3, lower panels, i-o). Cells were fixed and the ER and the Golgi apparatus were stained with antibodies directed against protein markers calnexin and giantin, respectively. In parallel, cells were stained with HA antibody to label HA-RAMP3 and a final wash with a solution at pH of 7.4 containing 50 mM NH₄Cl was performed in order to illuminate the entire SEP-CaSR population (as shown in Fig. 1B). The colors expected for merged areas are indicated. Images are representative of three independent experiments. Bar, 20 µm.