title: Application of the message-address concept to the docking of naltrexone and selective naltrexone-derived opioid antagonists into opioid receptor models.
abstract: A binding site model for the opioid family of G-protein coupled receptors (GPCRs) is proposed based on the message-address concept of ligand recognition. Using ligand docking studies of the universal opioid antagonist, naltrexone, the structural basis for "message' recognition is explored across all three receptor types, mu, delta, and kappa. The binding mode proposed and basis for selectivity are also rationalized using the naltrexone-derived ligands, naltrindole (NTI) and norbinaltorphimine (nor BNI). These ligands are docked to the receptor according to the common naltrexone core or message. The resulting orientation places key "address' elements in close proximity to amino acid residues critical to selectivity among receptors types. Selectivity is explained by sequence differences in the mu, delta, and kappa receptors at these recognition points. Support for the model is derived from site directed mutagenesis studies and ligand binding data for the opioid receptors and other related GPCRs.
authors.affiliation: Department of Medicinal Chemistry and Minnesota Supercomputer Institute, University of Minnesota, Minneapolis 55455, USA.
authors.forename: T G
authors.initials: TG
authors.lastname: Metzger
authors.forename: M G
authors.initials: MG
authors.lastname: Paterlini
authors.forename: P S
authors.initials: PS
authors.lastname: Portoghese
authors.forename: D M
authors.initials: DM
authors.lastname: Ferguson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D017124:Conserved Sequence; D019204:GTP-Binding Proteins / Q000378:metabolism; D008958:Models, Molecular; D008961:Models, Structural; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D009271:Naltrexone / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism*; D009292:Narcotic Antagonists / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D017465:Receptors, Opioid, delta / Q000737:chemistry* / Q000378:metabolism; D017473:Receptors, Opioid, kappa / Q000737:chemistry* / Q000378:metabolism
chemical_list: D009292:Narcotic Antagonists; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; C051844:norbinaltorphimine; D009271:Naltrexone; D019204:GTP-Binding Proteins; C055382:naltrindole