Expression and purification of β2AR in Sf9 cells The β2AR construct PN1 was expressed and purified as previously described39,42. In brief, Sf9 cells were infected with a PN1-containing baculovirus produced using the BestBac method. Cells were then collected and resuspended in chilled lysis buffer containing 10 mM HEPES, pH 7.4, 1 mM EDTA, 1 μM alprenolol and protease inhibitors