It is intended to provide a structural model of a complex of a ligand binding to a G protein-coupled receptor (GPCR); a method of constructing a three-dimensional structural model of an activation intermediate in this complex structural model; and a method of identifying, examining, searching for, evaluating or designing a ligand binding to the GPCR by using respective steric models. More specifically, a method wherein a three-dimensional structural model of a photoactivation intermediate of rhodopsin is constructed with the use of a molecule modeling software while using a three-dimensional structural coordinate of rhodopsin crystalline structure and paying attention to amino acid residues showing a high degree of conservation in GPCR, and then a structural model of another GPCR activation intermediate is formed by using the thus obtained three-dimensional structural model of the rhodopsin activation intermediate. Using the three-dimensional structural models thus obtained, a ligand which binds to the GPCR and serves as an agonist or an antagonist is identified, examined, searched for, evaluated or designed.
G PROTEIN-COUPLED RECEPTOR STRUCTURAL MODEL AND A METHOD OF DESIGNING LIGAND BINDING TO G PROTEIN-COUPLED RECEPTOR BY USING THE STRUCTURAL MODEL