Structure and function of the visual arrestin oligomer.

Hanson SM, Van Eps N, Francis DJ, Altenbach C, Vishnivetskiy SA, Arshavsky VY, Klug CS, Hubbell WL, Gurevich VV
EMBO J. 2007 26 (6): 1726-36

PMID: 17332750 · PMCID: PMC1829381 · DOI:10.1038/sj.emboj.7601614

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.

MeSH Terms (15)

Animals Arrestin Cattle Crystallization Humans Light Magnetic Resonance Spectroscopy Microtubules Models, Molecular Mutagenesis, Site-Directed Oligodeoxyribonucleotides Phosphorylation Protein Binding Rhodopsin Scattering, Radiation

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