Fig. 1
The dynamic conformational landscape of arrestins upon complex formation with ACKR3. a Cryo-EM structure of GRK5-phosphorylated ACKR3 with Arr2 (PDB: 9E82). The utilized ligand CXCL12LRHQ is shown in pink and captured membrane lipids are indicated in yellow. The resolved Arr2 structure with the GRK2-phosphorylated ACKR3 C-terminus (orange, PDB: 8TII) was positioned to symbolize the register shift of interacting with the more distal phosphorylation cluster, leading to a more loosely associated complex and hence yielding a higher flexibility. b Differential C-terminal cluster phosphorylation by GRK5 (proximal, T338-T341) and GRK2 (distal, T352-S355), interacting with Arr2 (light gray box). c Close-up of Arr2 finger loop region (FLR), inserting into the micelle membrane upon GRK5-mediated phosphorylation, which could not be fully resolved in complex with the GRK2-phosphorylated ACKR3 C-terminus. d Close-up of the C-edge region of Arr2 (PDB: 9E82) and Arr3 (PDB: 8TIL) upon interacting with the GRK5-phosphorylated ACKR3
