Fig. 7. Formation of a Gα_i:β-arrestin:AP-2 ternary complex.

(A to D) Transfected HEK293T cells expressing CXCR3, smBiT–β-arrestin2, Gα_i-LgBiT, and AP-2-mKO or cytosolic mKO were treated with vehicle or the indicated concentrations of CXCL11. (A) Complex BRET ratio for Gα_i:β-arrestin2:AP-2 after treatment with 100 nM CXCL11 or vehicle. (B) Transfected HEK293T cells were treated with vehicle or the indicated concentrations of CXCL11. Net BRET was measured 6 min after treatment. (C) Confocal microscopy analysis of CXCL11-induced complexes of Gα_i:β-arrestin:AP-2 in HEK293T cells transfected with mVenus-tagged Gα_i, mKO-tagged AP-2, and mCerulean-tagged β-arrestin2. Cells were imaged before (basal) and 20 min after treatment. Data are representative of three experiments per condition. For BRET experiments, data were normalized to both vehicle treatment and cytosolic mKO transfection conditions. (D) Scheme demonstrating the selective formation of Gα_i:β-arrestin:AP-2 rather than Gα_i:β-arrestin:ERK in response to the activation of CXCR3 by CXCL11.