Figure 1.

Effect of GIT1 overexpression on internalization of G protein-coupled receptors. (a) GIT1 overexpression affects the internalization of some G_s-coupled receptors. Wild-type (WT) and GIT1-overexpressing HEK293 cells transiently transfected with Flag-tagged β₂AR, β₁AR, Flag-VIP₁R, or A_2BR were incubated with isoproterenol (10 μM), VIP (0.1 μM), or adenosine (10 μM), respectively, for 30 min before incubation with antibodies as described in Materials and Methods. (b) Internalization of the G_i-coupled HA-μOR and HA-M2 MR was assessed in WT and GIT1-overexpressing 293 cells after a 30-min stimulation with etorphine (500 nM) or acetylcholine (ACh) (100 μM), respectively. (c) Internalization of the G_q-coupled Flag-ET_BR, the HA-AT_1AR, and HA-M1 MR was measured in WT and GIT1 overexpressing 293 cells after a 30-min stimulation with endothelin-1 (0.1 μM), angiotensin II (1 μM), or ACh (100 μM), respectively. Results are means ± SEM for 3–6 independent experiments done in duplicate. *, P < 0.001.