Crystallizing thinking about the beta2-adrenergic receptor.

Two recently determined crystal structures of the human beta2-adrenergic receptor (beta2AR) provide a long-awaited advance in the field of G protein-coupled receptor research. The beta2AR is only the second member of this, the largest family of receptors encoded in the human genome, whose structure has been solved. It follows structures of rhodopsin that were determined previously. Here we set these developments in historical context, discuss the daunting challenges that have been overcome, and appraise what has and has not been learned.