Functional dynamics of G-protein-coupled receptor shown by femtosecond X-ray scattering

The development of ultrafast X-ray free-electron lasers (XFELs) gives a new avenue to experimentally investigate protein dynamics in the picosecond and femtosecond time regimes. For G-protein-coupled receptors (GPCRs) like rhodopsin, an important question is how the rapid local dynamics of the ligand initiate the functional protein transitions. However, structural evidence is lacking because until now the extreme reaction speed has precluded direct X-ray diffraction approaches. Here we show how solution X-ray scattering combined with molecular simulations informs the functional dynamics of membrane proteins in ways that could previously only be imagined.