Opposing effects of inositol hexakisphosphate on rod arrestin and arrestin2 self-association.

Hanson SM, Vishnivetskiy SA, Hubbell WL, Gurevich VV
Biochemistry. 2008 47 (3): 1070-5

PMID: 18161994 · PMCID: PMC2562240 · DOI:10.1021/bi7021359

The robust cooperative formation of rod arrestin tetramers has been well-established, whereas the ability of other members of the arrestin family to self-associate remains controversial. Here, we used purified arrestins and multi-angle light scattering to quantitatively compare the propensity of the four mammalian arrestin subtypes to self-associate. Both non-visual and cone arrestins only form oligomers at very high non-physiological concentrations. However, inositol hexakisphosphate (IP6), a fairly abundant form of inositol in the cytoplasm, greatly facilitates self-association of arrestin2. Arrestin2 self-association equilibrium constants in the presence of 100 microM IP6 suggest that an appreciable proportion could exist in an oligomeric state but only in intracellular compartments where its concentration is 5-10-fold higher than average. In contrast to arrestin2, IP6 inhibits self-association of rod arrestin, indicating that the structure of these two tetramers in solution is likely different.

MeSH Terms (15)

Animals Arrestin Arrestins beta-Arrestins Cattle Chromatography, Gel Dimerization Humans Lasers Light Molecular Weight Phytic Acid Protein Binding Recombinant Proteins Scattering, Radiation

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