Heterodyne holographic microscopy of gold particles

We report experimental results on heterodyne holographic microscopy of subwavelength-sized gold particles. The apparatus uses continuous green laser illumination of the metal beads in a total internal reflection configuration for dark-field operation. Detection of the scattered light at the illumination wavelength on a charge-coupled device array detector enables 3D localization of brownian particles in wate

Homo- and Hetero-oligomerization of β-Arrestins in Living Cells

International audienceArrestins 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