Fig. 5: β-arrestin translocation to early endosomes is controlled by the receptor C-terminus.

Control and ΔQ-GRK cells, overexpressing GRK2, GRK6 or no GRKs (empty vector (EV)-transfected) were transfected with the indicated receptor-CFP, β-arrestin-YFP and early endosome marker Rab5-mCherry. Confocal images were taken before (basal) and after 15 min of specified ligand. a Representative images for all receptors, expressed in Control cells. b The co-localization of Rab5 with β-arrestin2 in Control cells was quantified in over 28 images for each condition using Squassh and SquasshAnalyst^44,45. Data are presented as mean fold change in co-localization (signal) + SEM, normalized to the respective unstimulated (basal) ΔQ-GRK + EV condition. Statistical comparison between basal and stimulated values was performed using a two-way ANOVA, followed by a Sidak’s test (ns not significant; ****p < 0.0001). Detailed results, also for the two-way ANOVA, followed by a Tukey’s test to compare basal and stimulated values between different conditions, can be accessed in Supplementary Tables 3–5. c–f Analogous to the data shown in (b), the fold change in co-localization (signal) was analyzed for the receptor or β-arrestin2 with Rab5, as fold change over the respective basal ΔQ-GRK + EV condition for each receptor and GRK condition (Control, ΔQ-GRK + EV, +GRK2, +GRK6). The stimulated values for receptor–Rab5 co-localization are show on the x-axis and for β-arrestin2–Rab5 co-localization on the y-axis. For both dimension, the data points were normalized to the respective maximum (for receptor–Rab5 co-localization: V2b2 in Control cells, for β-arrestin2–Rab5 co-localization: b2V2 in Control cells) and are shown in percent. Source data are provided as a Source Data file.