Constitutive activity and inverse agonists of G protein-coupled receptors: a current perspective.

Over the last decade, the ability to detect agonist-independent signal transduction by G protein-coupled receptors has in turn resulted in the detection and study of ligands able to block this activity. Such ligands are generically described as inverse agonists. Considerable attention has recently been devoted to the presence and roles of endogenous antagonist/inverse agonists and the concept that inverse agonists may have specific therapeutic benefits compared with neutral antagonists.