Crystal Structure of β-Arrestin 2 in Complex with CXCR7 Phosphopeptide

β-Arrestins (βarrs) critically regulate G-protein-coupled receptor (GPCR) signaling and trafficking. βarrs have two isoforms, βarr1 and βarr2. Receptor phosphorylation is a key determinant for the binding of βarrs, and understanding the intricate details of receptor-βarr interaction is the next frontier in GPCR structural biology. The high-resolution structure of active βarr1 in complex with a phosphopeptide derived from GPCR has been revealed, but that of βarr2 remains elusive. Here, we present a 2.3-Å crystal structure of βarr2 in complex with a phosphopeptide (C7pp) derived from the carboxyl terminus of CXCR7. The structural analysis of C7pp-bound βarr2 reveals key differences from the previously determined active conformation of βarr1. One of the key differences is that C7pp-bound βarr2 shows a relatively small inter-domain rotation. Antibody-fragment-based conformational sensor and hydrogen/deuterium exchange experiments further corroborated the structural features of βarr2 and suggested that βarr2 adopts a range of inter-domain rotations. [Display omitted] •The structure of β-arrestin 2 bound to CXCR7 phosphopeptide (C7pp) was solved•The C7pp-bound β-arrestin 2 shows small inter-domain rotation•The three C7pp phosphates bind with the positively charged residues on β-arrestin 2•The phosphate-binding pocket around Arg148 recognizes the first phosphate of C7pp β-arrestins (βarrs) critically regulate GPCR signaling and trafficking. Min et al. present a 2.3-Å crystal structure of βarr2 in complex with a phosphopeptide (C7pp) derived from the carboxyl terminus of CXCR7, revealing that C7pp-bound βarr2 shows a relatively small inter-domain rotation compared with V2Rpp-bound βarr1.