Allosterism and cannabinoid CB(1) receptors: the shape of things to come.

In 2005, the first evidence was obtained that the cannabinoid CB(1) receptor contains an allosteric binding site. The site can be recognized by synthetic small molecules, which display a markedly divergent effect on orthosteric ligand affinity versus efficacy; these small molecules are allosteric enhancers of agonist binding affinity and allosteric inhibitors of agonist signalling efficacy. Allosteric modulation heralds a new approach to the manipulation of the endocannabinoid system for therapeutic benefit; it promises to augment the existing portfolio of selective direct agonists, competitive antagonists and enzyme inhibitors.