Rhodopsin is a prototypical G-protein coupled receptor that initiates photo-transduction in the retina of the eye. Like many other G protein-coupled receptors, rhodopsin appears to form oligomers in the membrane. The clearest demonstration that rhodopsin forms oligomers comes from atomic force microscopy images displaying large arrays of rhodopsin monomers. It has been speculated, however, that oligomers observed in these images are due to phase separation occurring in membranes at temperatures below 37 °C. In the work presented here, we explored in detail the oligomeric status of rhodopsin and its dependency on temperature using spectrally resolved Fluorescent Resonance Energy Transfer (FRET) [1] in Chinese hamster ovary cells. As a control, we also investigated a G188R mutant rhodopsin. This mutaton causes misfolding of rhodopsin and leads to the retinal degenerative disorder retinitis pigmentosa. Our results suggest that the quaternary structure of wild-type rhodopsin is vastly different compared to that of the misfolded mutant rhodopsin.

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A.K. Mishra, M. Gragg, M.R. Stoneman, G. Biener, J.A. Oliver, P. Miszta, S. Filipek, V. Raicu, P. Park, Quaternary structures of opsin in live cells revealed by FRET spectrometry, Biochemical Journal 473 (2016) 3819-3836

K. King, V. Raicu and K. Hristova, Understanding the FRET signatures of Interacting Membrane Proteins, Journal of Biological Chemistry 292 (2017) 5291-5310

M.R. Stoneman, J.D. Paprocki, G. Biener, A. Shevade, S. Kuchin, and V. Raicu, Quaternary structure of the yeast pheromone receptor Ste2 in living cells. BBA Biomembranes 1859 (2017) 1456-1464

MJ Corby, M.R. Stoneman, G. Biener, J.D. Paprocki, R. Kolli, V. Raicu, D.N. Frick, Quantitative micro-spectroscopic imaging reveals viral and cellular RNA helicase interactions in live cells. Journal of Biological Chemistry 292 (2017) 11165-11177