title: Three-dimensional molecular models of the hMC1R melanocortin receptor: complexes with melanotropin peptide agonists.
abstract: Three-dimensional molecular models of the human melanocortin receptor (hMC1R) have been developed based upon the electron cryo-microscopic structure of bacteriorhodopsin and the electron density footprint of bovine rhodopsin. alpha-Melanocyte-stimulating hormone, Ac-Ser-Tyr-Ser-Met4-Glu-His-Phe7-Arg-Trp-Gly-Lys-Pro-Val-NH2 (alpha-MSH, alpha-melanotropin), and the superpotent, prolonged acting agonists, Ac-Ser-Tyr-Ser-Nle4-Glu-His-DPhe7-Arg-Trp-Gly-Lys-Pro-Val-NH2 (NDP-MSH) and Ac-Nle4-c[Asp5-His6-DPhe7-Arg8-Trp9-Lys10]-NH2 (MTII), have been modeled into the proposed binding sites with specific ligand-receptor interactions identified. The melanotropin sidechain pharmacophores, DPhe7 and Trp9, are proposed to interact with a hydrophobic network of receptor aromatic residues in transmembrane regions 4, 5, 6, and 7. In addition, a hydrophilic network involving the ligand Arg8 and polar receptor residues located in transmembrane regions 2 and 3 were identified. Biological studies on alpha-MSH, NDP-MSH, MTII, and related peptides have been correlated with the proposed hMC1R model in terms of agonism, affinity, and prolongation. Finally, limited MC1R mutagenesis studies comparing alpha-MSH and NDP-MSH are interpreted within the context of the proposed hMC1R models.
authors.affiliation: Department of Chemistry, University of Arizona, Tucson 85721, USA.
authors.forename: C
authors.initials: C
authors.lastname: Haskell-Luevano
authors.forename: T K
authors.initials: TK
authors.lastname: Sawyer
authors.forename: S
authors.initials: S
authors.lastname: Trumpp-Kallmeyer
authors.forename: J A
authors.initials: JA
authors.lastname: Bikker
authors.forename: C
authors.initials: C
authors.lastname: Humblet
authors.forename: I
authors.initials: I
authors.lastname: Gantz
authors.forename: V J
authors.initials: VJ
authors.lastname: Hruby
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001436:Bacteriorhodopsins / Q000737:chemistry; D002417:Cattle; D006801:Humans; D009074:Melanocyte-Stimulating Hormones / Q000819:agonists*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry / Q000494:pharmacology; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D018043:Receptors, Corticotropin / Q000737:chemistry* / Q000378:metabolism*; D044101:Receptors, Melanocortin; D012243:Rhodopsin / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D013698:Templates, Genetic; D000521:alpha-MSH / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology
chemical_list: D009842:Oligopeptides; D010455:Peptides; D018043:Receptors, Corticotropin; D044101:Receptors, Melanocortin; C105974:acetyl-norleucyl(4)-(aspartyl(5)-histidyl(6)-phenylalanyl(7)-arginyl(8)-tryptophyl(9)-lysyl(10))cyclo-alpha-MSH(4-10)amide; D001436:Bacteriorhodopsins; D000521:alpha-MSH; C027756:MSH, 4-Nle-7-Phe-alpha-; D009074:Melanocyte-Stimulating Hormones; D012243:Rhodopsin