Fig. 10. ß₁AR and ß₂AR recycle with similar kinetics but differ in sensitivity to monensin. Cells stably expressing ß₁AR and ß₂AR were treated with 1 µM ISO for 15-30 minutes to induce maximum internalization, washed to remove the agonist and allowed to recycle for the indicated times. The cells were then assayed for surface receptors as described in Materials and Methods. Recycling of ß₁AR () and ß₂AR () in (A) BHK cells and (B) Arr2-BHK cells. (C) Recycling of ß₁AR (,) and ß₂AR (,) in control and monensin-treated HEK 293 cells. Cells were treated with 100 µM monensin (closed symbols) for 30 minutes before adding agonist, and monensin was present during the recycling period. (D) Summary of ßAR recycling in control and monensin-treated cells. Values are expressed as the percentage recycling of internalized receptors, and represent the means±s.e.m. of 3-5 independent experiments. Differences between control and monensin-treated ß₁AR-expressing cells were not significant. ^*P<0.01; ^**P<0.001.