Arresting Developments in Biased Signaling.

The ability to design 'biased' drugs that selectively activate G protein-coupled receptor (GPCR) signaling pathways beneficial in treating a disease, while limiting their side effects, is of broad significance. Lee et al. move us a step closer to this important goal by identifying structural differences in the beta(1)-adrenoceptor in complex with beta-arrestin 1 versus a G protein-mimicking nanobody.