Molecular Determinants of Ligand Binding to the Human Melanocortin-4 Receptor
| Autor: | Chris J. Dickinson, C. Mao, L. H. T. Van Der Ploeg, Ralph T. Mosley, T. M. Fong, Michael R. Tota, Ira Gantz, Ying Kui Yang, Ji Yao Li |
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| Rok vydání: | 2000 |
| Předmět: |
Models
Molecular Threonine Agonist Receptors Peptide Protein Conformation Stereochemistry medicine.drug_class Molecular Sequence Data Amino Acids Cyclic Biology Ligands Biochemistry medicine Enzyme-linked receptor Humans Agouti-Related Protein 5-HT5A receptor Amino Acid Sequence Cysteine GABBR2 GABBR1 Receptor Binding Sites Mutagenesis Proteins Peptide Fragments Recombinant Proteins Melanocortin 4 receptor alpha-MSH Mutagenesis Site-Directed Intercellular Signaling Peptides and Proteins Receptor Melanocortin Type 4 Protein Binding |
| Zdroj: | Biochemistry. 39:14900-14911 |
| ISSN: | 1520-4995 0006-2960 |
| DOI: | 10.1021/bi001684q |
| Popis: | To elucidate the molecular basis for the interaction of ligands with the human melanocortin-4 receptor (hMC4R), agonist structure-activity studies and receptor point mutagenesis were performed. Structure-activity studies of [Nle(4), D-Phe(7)]-alpha-melanocyte stimulating hormone (NDP-MSH) identified D-Phe7-Arg8-Trp9 as the minimal NDP-MSH fragment that possesses full agonist efficacy at the hMC4R. In an effort to identify receptor residues that might interact with amino acids in this tripeptide sequence 24 hMC4R transmembrane (TM) residues were mutated (the rationale for choosing specific receptor residues for mutation is outlined in the Results section). Mutation of TM3 residues D122 and D126 and TM6 residues F261 and H264 decreased the binding affinity of NDP-MSH 5-fold or greater, thereby identifying these receptor residues as sites potentially involved in the sought after ligand-receptor interactions. By examination of the binding affinities and potencies of substituted NDP-MSH peptides at receptor mutants, evidence was found that core melanocortin peptide residue Arg8 interacts at a molecular level with hMC4R TM3 residue D122. TM3 mutations were also observed to decrease the binding of hMC4R antagonists. Notably, mutation of TM3 residue D126 to alanine decreased the binding affinity of AGRP (87-132), a C-terminal derivative of the endogenous melanocortin antagonist, 8-fold, and simultaneous mutations D122A/D126A completely abolished AGRP (87-132) binding. In addition, mutation of TM3 residue D122 or D126 decreased the binding affinity of hMC4R antagonist SHU 9119. These results provide further insight into the molecular determinants of hMC4R ligand binding. |
| Databáze: | OpenAIRE |
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