Fig. 4.

Quantitative assessment of V2R and V1aR internalization induced by F180. HEK 293T cells expressing Myc-V2R, HA-V1aR, or Myc-V2R plus HA-V1aR were treated or not with the V1aR selective agonist F180 (600 nM) at 37°C for 30 min to promote internalization of the receptors. The cell surface Myc epitope-tagged V2R (A) or HA epitope-tagged V1aR (B) were detected by ELISA as described under Materials and Methods. The extent of internalization was determined by measuring the cell surface receptor before and after F180 stimulation and was expressed as the loss of cell surface expression (percentage of control). Experimental conditions were established so that V2R and V1aR were expressed at ≈150 fmol per well whether expressed alone or in combination. All values correspond to the mean ± SEM calculated from at least seven independent experiments.