title: Identification of receptor binding-induced conformational changes in non-visual arrestins.
abstract: The non-visual arrestins, arrestin-2 and arrestin-3, belong to a small family of multifunctional cytosolic proteins. Non-visual arrestins interact with hundreds of G protein-coupled receptors (GPCRs) and regulate GPCR desensitization by binding active phosphorylated GPCRs and uncoupling them from heterotrimeric G proteins. Recently, non-visual arrestins have been shown to mediate G protein-independent signaling by serving as adaptors and scaffolds that assemble multiprotein complexes. By recruiting various partners, including trafficking and signaling proteins, directly to GPCRs, non-visual arrestins connect activated receptors to diverse signaling pathways. To investigate arrestin-mediated signaling, a structural understanding of arrestin activation and interaction with GPCRs is essential. Here we identified global and local conformational changes in the non-visual arrestins upon binding to the model GPCR rhodopsin. To detect conformational changes, pairs of spin labels were introduced into arrestin-2 and arrestin-3, and the interspin distances in the absence and presence of the receptor were measured by double electron electron resonance spectroscopy. Our data indicate that both non-visual arrestins undergo several conformational changes similar to arrestin-1, including the finger loop moving toward the predicted location of the receptor in the complex as well as the C-tail release upon receptor binding. The arrestin-2 results also suggest that there is no clam shell-like closure of the N- and C-domains and that the loop containing residue 136 (homolog of 139 in arrestin-1) has high flexibility in both free and receptor-bound states.
authors.affiliation: From the Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 and.
authors.forename: Ya
authors.initials: Y
authors.lastname: Zhuo
authors.affiliation: the Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Vishnivetskiy
authors.affiliation: the Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
authors.forename: Xuanzhi
authors.initials: X
authors.lastname: Zhan
authors.affiliation: the Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
authors.forename: Vsevolod V
authors.initials: VV
authors.lastname: Gurevich
authors.affiliation: From the Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 and candice@mcw.edu.
authors.forename: Candice S
authors.initials: CS
authors.lastname: Klug
mesh_terms: D019390:Arrestins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012243:Rhodopsin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013113:Spin Labels
chemical_list: D019390:Arrestins; D013113:Spin Labels; C082333:arrestin3; D012243:Rhodopsin
keywords: Arrestin; Electron Paramagnetic Resonance (EPR); G Protein-coupled Receptor (GPCR); Rhodopsin; Spectroscopy