PT - JOURNAL ARTICLE AU - Gérard Benoit AU - Austin Cooney AU - Vincent Giguere AU - Holly Ingraham AU - Mitch Lazar AU - George Muscat AU - Thomas Perlmann AU - Jean-Paul Renaud AU - John Schwabe AU - Frances Sladek AU - Ming-Jer Tsai AU - Vincent Laudet TI - International Union of Pharmacology. LXVI. Orphan Nuclear Receptors AID - 10.1124/pr.58.4.10 DP - 2006 Dec 01 TA - Pharmacological Reviews PG - 798--836 VI - 58 IP - 4 4099 - http://pharmrev.aspetjournals.org/content/58/4/798.short 4100 - http://pharmrev.aspetjournals.org/content/58/4/798.full SO - Pharmacol Rev2006 Dec 01; 58 AB - Half of the members of the nuclear receptors superfamily are so-called “orphan” receptors because the identity of their ligand, if any, is unknown. Because of their important biological roles, the study of orphan receptors has attracted much attention recently and has resulted in rapid advances that have helped in the discovery of novel signaling pathways. In this review we present the main features of orphan receptors, discuss the structure of their ligand-binding domains and their biological functions. The paradoxical existence of a pharmacology of orphan receptors, a rapidly growing and innovative field, is highlighted.