Homo- and Hetero-oligomerization of β-Arrestins in Living Cells
Résumé
Arrestins are important proteins, which regulate the function of serpentine heptahelical receptors and contribute to multiple signaling pathways downstream of receptors. The ubiquitous β-arrestins are believed to function exclusively as monomers, although self-association is assumed to control the activity of visual arrestin in the retina, where this isoform is particularly abundant. Here the oligomerization status of β-arrestins was investigated using different approaches, including co-immunoprecipitation of epitope-tagged β-arrestins and resonance energy transfer (BRET and FRET) in living cells. At steady state and at physiological concentrations, β-arrestins constitutively form both homo- and hetero-oligomers. Co-expression of β-arrestin2 and β-arrestin1 prevented β-arrestin1 accumulation into the nucleus, suggesting that hetero-oligomerization may have functional consequences. Our data clearly indicate that β-arrestins can exist as homo- and hetero-oligomers in living cells and raise the hypothesis that the oligomeric state may regulate their subcellular distribution and functions.
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