GPCR proteins undergo changes in their shape (conformation) upon ligand binding. Rhodopsin in the eye retina detects light using its photon-sensitive retinal moiety, while olfactory receptors detect fragrant molecules, which we breathe in. In both cases this triggers signals, which are processed by our brains into senses of vision and smell (to examine more scientifically correct cartoons of GPCR signalling dangerous intellectuals should press the links I provided below)
The 2012 Nobel Prize in Chemistry was awarded to Robert J Lefkowitz and Brian K Kobilka for their mechanistic work on G-protein-coupled receptors or GPCRs.… Read the rest