title: Structure and function of the visual arrestin oligomer.
abstract: A distinguishing feature of rod arrestin is its ability to form oligomers at physiological concentrations. Using visible light scattering, we show that rod arrestin forms tetramers in a cooperative manner in solution. To investigate the structure of the tetramer, a nitroxide side chain (R1) was introduced at 18 different positions. The effects of R1 on oligomer formation, EPR spectra, and inter-spin distance measurements all show that the structures of the solution and crystal tetramers are different. Inter-subunit distance measurements revealed that only arrestin monomer binds to light-activated phosphorhodopsin, whereas both monomer and tetramer bind microtubules, which may serve as a default arrestin partner in dark-adapted photoreceptors. Thus, the tetramer likely serves as a 'storage' form of arrestin, increasing the arrestin-binding capacity of microtubules while readily dissociating to supply active monomer when it is needed to quench rhodopsin signaling.
authors.affiliation: Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Hanson
authors.forename: Ned
authors.initials: N
authors.lastname: Van Eps
authors.forename: Derek J
authors.initials: DJ
authors.lastname: Francis
authors.forename: Christian
authors.initials: C
authors.lastname: Altenbach
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Vishnivetskiy
authors.forename: Vadim Y
authors.initials: VY
authors.lastname: Arshavsky
authors.forename: Candice S
authors.initials: CS
authors.lastname: Klug
authors.forename: Wayne L
authors.initials: WL
authors.lastname: Hubbell
authors.forename: Vsevolod V
authors.initials: VV
authors.lastname: Gurevich
mesh_terms: D000818:Animals; D019393:Arrestin / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D002417:Cattle; D003460:Crystallization; D006801:Humans; D008027:Light; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008870:Microtubules / Q000378:metabolism; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D010766:Phosphorylation; D011485:Protein Binding; D012243:Rhodopsin / Q000378:metabolism; D012542:Scattering, Radiation
chemical_list: D019393:Arrestin; D009838:Oligodeoxyribonucleotides; D012243:Rhodopsin