Unraveling the hidden temporal range of fast β2-adrenergic receptor mobility by time-resolved fluorescence

The mobility of the beta 2-adrenergic receptor, from the nanosecond to the second range, is revealed by combining several fluorescent spectroscopy techniques. These data also show a previously hidden mobility of this GPCR. G-protein-coupled receptors (GPCRs) are hypothesized to possess molecular mobility over a wide temporal range. Until now the temporal range has not been fully accessible due to the crucially limited temporal range of available methods. This in turn, may lead relevant dynamic constants to remain masked. Here, we expand this dynamic range by combining fluorescent techniques using a spot confocal setup. We decipher mobility constants of beta(2)-adrenergic receptor over a wide time range (nanosecond to second). Particularly, a translational mobility (10 mu m(2)/s), one order of magnitude faster than membrane associated lateral mobility that explains membrane protein turnover and suggests a wider picture of the GPCR availability on the plasma membrane. And a so far elusive rotational mobility (1-200 mu s) which depicts a previously overlooked dynamic component that, despite all complexity, behaves largely as predicted by the Saffman-Delbruck model.