Figure 6.

Detection of Gα_i protein activity in HEK293T cells by BRET-based G protein biosensor. (A) Fusion of Nluc to Gα_i2 subunit and cpVenus to Gγ subunit allows BRET detection of the heterotrimeric G protein complex. Agonist binding to the H₄R leads to activation and dissociation of heterotrimeric G proteins, resulting in reduced BRET signal. (B) BRET measurements in HEK293T cells transiently co-expressing HA-H₄R and G protein biosensor (red trace) or HA-H₄R, V2-TSPAN4 and G protein biosensor (blue trace), upon stimulation with histamine for 20 min. Data are displayed as mean ± SEM from 3 independent experiments performed in triplicate.