Structure and function of the visual arrestin oligomer.
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.
Hanson
Susan M
SM
Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA.
Van Eps
Ned
N
Francis
Derek J
DJ
Altenbach
Christian
C
Vishnivetskiy
Sergey A
SA
Arshavsky
Vadim Y
VY
Klug
Candice S
CS
Hubbell
Wayne L
WL
Gurevich
Vsevolod V
VV
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
D019393:Arrestin; D009838:Oligodeoxyribonucleotides; D012243:Rhodopsin