title: Structure of active β-arrestin-1 bound to a G-protein-coupled receptor phosphopeptide.
abstract: The functions of G-protein-coupled receptors (GPCRs) are primarily mediated and modulated by three families of proteins: the heterotrimeric G proteins, the G-protein-coupled receptor kinases (GRKs) and the arrestins. G proteins mediate activation of second-messenger-generating enzymes and other effectors, GRKs phosphorylate activated receptors, and arrestins subsequently bind phosphorylated receptors and cause receptor desensitization. Arrestins activated by interaction with phosphorylated receptors can also mediate G-protein-independent signalling by serving as adaptors to link receptors to numerous signalling pathways. Despite their central role in regulation and signalling of GPCRs, a structural understanding of β-arrestin activation and interaction with GPCRs is still lacking. Here we report the crystal structure of β-arrestin-1 (also called arrestin-2) in complex with a fully phosphorylated 29-amino-acid carboxy-terminal peptide derived from the human V2 vasopressin receptor (V2Rpp). This peptide has previously been shown to functionally and conformationally activate β-arrestin-1 (ref. 5). To capture this active conformation, we used a conformationally selective synthetic antibody fragment (Fab30) that recognizes the phosphopeptide-activated state of β-arrestin-1. The structure of the β-arrestin-1-V2Rpp-Fab30 complex shows marked conformational differences in β-arrestin-1 compared to its inactive conformation. These include rotation of the amino- and carboxy-terminal domains relative to each other, and a major reorientation of the 'lariat loop' implicated in maintaining the inactive state of β-arrestin-1. These results reveal, at high resolution, a receptor-interacting interface on β-arrestin, and they indicate a potentially general molecular mechanism for activation of these multifunctional signalling and regulatory proteins.
authors.affiliation: Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Arun K
authors.initials: AK
authors.lastname: Shukla
authors.forename: Aashish
authors.initials: A
authors.lastname: Manglik
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Kruse
authors.forename: Kunhong
authors.initials: K
authors.lastname: Xiao
authors.forename: Rosana I
authors.initials: RI
authors.lastname: Reis
authors.forename: Wei-Chou
authors.initials: WC
authors.lastname: Tseng
authors.forename: Dean P
authors.initials: DP
authors.lastname: Staus
authors.forename: Daniel
authors.initials: D
authors.lastname: Hilger
authors.forename: Serdar
authors.initials: S
authors.lastname: Uysal
authors.forename: Li-Yin
authors.initials: LY
authors.lastname: Huang
authors.forename: Marcin
authors.initials: M
authors.lastname: Paduch
authors.forename: Prachi
authors.initials: P
authors.lastname: Tripathi-Shukla
authors.forename: Akiko
authors.initials: A
authors.lastname: Koide
authors.forename: Shohei
authors.initials: S
authors.lastname: Koide
authors.forename: William I
authors.initials: WI
authors.lastname: Weis
authors.forename: Anthony A
authors.initials: AA
authors.lastname: Kossiakoff
authors.forename: Brian K
authors.initials: BK
authors.lastname: Kobilka
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Lefkowitz
mesh_terms: D000818:Animals; D019390:Arrestins / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism*; D018360:Crystallography, X-Ray; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D008958:Models, Molecular; D010748:Phosphopeptides / Q000737:chemistry* / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D055550:Protein Stability; D051381:Rats; D017483:Receptors, Vasopressin / Q000737:chemistry*; D012399:Rotation; D000071559:beta-Arrestin 1; D000071557:beta-Arrestins
chemical_list: C000605253:ARRB1 protein, human; C000605256:Arrb1 protein, rat; D019390:Arrestins; D007140:Immunoglobulin Fab Fragments; D010748:Phosphopeptides; D017483:Receptors, Vasopressin; D000071559:beta-Arrestin 1; D000071557:beta-Arrestins