FIGURE 4.

The effect of β-arrestin 2 expression on receptor recognition. CHO cells stably expressing FLAG-tagged δOR (A) or μOR (B) transfected with β-arrestin 2 cDNA were treated with 1 μm deltorphin II or DAMGO for 30 min at 37 °C, and the extent of antibody recognition by δOR (5A2) and μOR (4D6) mAbs monitored by ELISA as described under “Experimental Procedures.” C, SK-N-SH cells endogenously expressing μOR or δOR transfected with control siRNA or β-arrestin 2 siRNA were treated with 1 μm DAMGO or deltorphin II for 30 min at 37 °C and the extent of antibody recognition by μOR (4D6) and δOR (5A2) mAbs monitored by ELISA as described under “Experimental Procedures.” Results are mean ± S.E. of three experiments in triplicate. ^**, p < 0.01; ^***, p < 0.001, Dunnett's test.