The invention disclosed in this patent document relates to transmembrane
receptors, more particularly to a human G protein-coupled receptor for
which the endogenous ligand is known ("known GPCRs"), and most
particularly to mutated (non-endogenous) versions of the known GPCRs for
use, most preferably in screening assays for the direct identification of
candidate compounds as inverse agonists, agonists and partial agonists.