Total protein expression of the OR51E1 constructs in HEK 293T cells was measured by enzyme-linked immunosorbent assay (ELISA), as previously reported (34 (link),66 (link)). Cells were grown in a poly-l-lysine 96-well-plate (black plate with clear bottoms) and transfected with OR51E1 or OR51E1 variants with RTP1S and with or without Golf. After 24-hour transfection, cells were fixed, permeabilized, and incubated with mouse monoclonal anti-flag antibody (M2, catalog no. F1802, MilliporeSigma) at 1:100 dilution and detected with anti-mouse horseradish peroxidase (HRP)–conjugated secondary antibody (catalog no. 115-035-146, the Jackson Laboratory) at 1:8000 dilution. HRP levels were measured with 1-Step Ultra TMB (3,3′,5,5′-tetramethylbenzidine; catalog no. 34028, Thermo Fisher Scientific) at excitation of 450 nm.