FIGURE 4.

Molecular model of the human GnRH receptor-GnRH I complex. A, A βII′-turn conformation of GnRH I derived from the NMR structure (PDB code 1YY1) was docked into the receptor model in the active conformation derived from the active state of bovine rhodopsin (3DQB) according to experimentally identified intermolecular interactions between GnRH I (gray) and the receptor contact sites (yellow). pGlu¹ of GnRH I interacts with Asn^212(5.39); His² interacts with Asp^98(2.61) and Lys^121(3.32); Tyr⁵ interacts with Tyr^290(6.58); Arg⁸ interacts with Asp^302(7.32); and Pro⁹-Gly¹⁰NH₂ interacts with Arg^38(1.35) and Asn^102(2.65). The H-bonds are indicated by dashed lines. The model suggests that the side chain of Gln^174(4.60) makes H-bond contacts with pGlu¹ of GnRH, whereas the aromatic ring of Phe^178(4.64) interacts with the aromatic ring of Trp³ in GnRHs through displaced pi-stacking connections. B, NMR (cyan) and docked (gray) structures of GnRH I showing that the docked GnRH I has a trajectory similar to that of the NMR structure.