CLR endocytosis. (A–D) BRET assays of CLR-RLuc8 and βARR2-YFP (A), Rab5a-Venus and KRas-Venus (B and D), and Rab11-Venus (C) proximity in HEK cells. (D) CLR-RLuc8 and Rab5a-Venus or KRas-Venus BRET (100 nM CGRP, 15 min). (E) Cell-surface HA-CLR ELISA in HEK cells (100 nM CGRP, 15 min). n = 3 experiments. (F) Confocal images of HA-CLR-IR and EEA1-IR in HEK cells. Dy4a, dynamin inhibitor; DynK44E, dominant-negative dynamin; inact, inactive analog; PS2, clathrin inhibitor. n = 3–6 experiments. *P < 0.05, **P < 0.01, ***P < 0.005, ****P < 0.0001 to basal or control. ANOVA, Sidak’s test.