[G-protein-binding receptors]

All G protein-binding receptors have closely similar structures. They all include seven membrane-spanning segments, with significant sequence homologies between receptors. G. Vassart and co-workers made use of this fact to devise a polymerase chain reaction (PCR) method for cloning G protein-binding receptors. This method has been used to sequence a large number of hormone receptors including the thyrotropin (TSH) receptor. The process used to isolate this receptor is described, as well as newly gained insights into the pathophysiology of autoimmune thyroid gland diseases. For some sequenced receptors, the natural ligands were not known. This required development of strategies designed at identifying the functions of these receptors. An illustrative example of this approach is the characterization of A1 and A2 receptors for adenosine.