Time-resolved functional expansion of visual rhodopsin detected by x-ray scattering

Visual rhodopsin is an excellent model system to understand spatio-temporal dynamics of class A G-protein-coupled receptors (GPCRs). We aim to understand the mechanistic details of how the local changes in the retinal cofactor propagate to become large scale conformational changes leading to visual signaling. Our hypothesis was that a volumetric expansion occurs in the light-activation process [1]. Here we show the first time-resolved X-ray scattering-based detection of the expansion of rhodopsin leading to the signaling state.