Figure 4.

Effect of chemical crosslinking on β₂AR dimerization. (A) A FLAG-tagged β₂AR was immunoprecipitated from cells treated or not for 30 min with the cell-impermeable chemical crosslinker BS3 by using a polyclonal anti-β₂AR antibody (Santa Cruz Biotechnology). Immunoprecipitates then were resolved by SDS/PAGE, and the receptor was detected by Western blot analysis by using the monoclonal anti-FLAG antibody (Sigma). (B) BRET ratio measured in cells expressing the indicated constructs. Cells were treated or not with BS3 for 30 min before the addition of coelenterazine. The data represent the mean ± SEM of four independent readings.