Chembiochem : a European journal of chemical biology
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Three types of opioid receptors-mu, delta, and kappa-belong to the rhodopsin subfamily in the G protein-coupled receptor superfamily. With the recent characterization of the high-resolution X-ray crystal structure of bovine rhodopsin, considerable attention has been focused on molecular modeling of these transmembrane proteins. In this study, a homology model of the mu opioid receptor was constructed based on the X-ray crystal structure of bovine rhodopsin. ⋯ The opioid ligand naltrexone was docked into the optimized model, and the critical amino acid residues for binding were identified. The mu opioid receptor homology model optimized in a complete membrane-aqueous system should provide a good starting point for further characterization of the binding modes for opioid ligands. Furthermore, the method developed herein will be applicable to molecular model building to other opioid receptors as well as other GPCRs.