Fig. 6

Mechanisms of arrestin activation and domain rotation. a Overlay of the hydrophobic core between β-strands supporting the finger loop (pink) and the C-loop (green) in the active arrestin-3 and in the basal arrestin-3 (gray, PDB 3P2D⁶). b Conformation of hydrophobic core between β-strands surrounding the finger loop and the C-loop in the basal arrestin-3 (PDB 3P2D⁶). c–e The inter-domain twist realigns the arrestin switch regions. In each panel, the switch regions are darker elements; magenta balls mark equivalent residues. c Basal arrestin-3 (PDB 3P2D⁶). d IP₆-activated arrestin-3 with a 17.7° inter-domain rotation. e p44 arrestin-1 (PDB 4J2Q¹⁰) with a 21° inter-domain rotation