Conserved HisVI-17 of the NK-1 receptor is involved in binding of non-peptide antagonists but not substance P.
Residue number 17 in transmembrane segment VI has been shown to be crucial for the binding of agonists in G-protein-coupled receptors for the monoamines. In many peptide receptors a histidyl residue has been conserved at this position. We find that replacement of HisVI-17 in the NK-1 receptor with either glutamine, phenylalanine, or alanine has no apparent effect on the binding of the natural peptide ligand substance P or on the agonist induced increase in inositolphosphate turnover. However, the binding of certain non-peptide antagonists was impaired; for example, replacement of HisVI-17 with alanine decreased the affinity for FK888 and RP67,580 5- to 12-fold, respectively. A glutamine side chain was a good substitute for the imidazole in the binding of all non-peptide antagonists. It is concluded that the conserved HisVI-17 in the NK-1 receptor is involved in the binding of certain non-peptide antagonists, but is not important for the action of the natural peptide agonist, substance P.
Zoffmann
S
S
University Department of Clinical Chemistry, Rigshospitalet, Copenhagen, Denmark.
Gether
U
U
Schwartz
T W
TW
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D001713:Biphenyl Compounds / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D017124:Conserved Sequence; D004151:Dipeptides / Q000378:metabolism; D006801:Humans; D007211:Indoles / Q000378:metabolism; D054833:Isoindoles; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D064729:Neurokinin-1 Receptor Antagonists; D010880:Piperidines / Q000378:metabolism; D017433:Protein Structure, Secondary; D011812:Quinuclidines / Q000378:metabolism; D018040:Receptors, Neurokinin-1 / Q000737:chemistry* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013373:Substance P / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014162:Transfection
D001713:Biphenyl Compounds; D004151:Dipeptides; D007211:Indoles; D054833:Isoindoles; D064729:Neurokinin-1 Receptor Antagonists; D010880:Piperidines; D011812:Quinuclidines; D018040:Receptors, Neurokinin-1; D011994:Recombinant Proteins; C071693:7,7-diphenyl-2-(1-imino-2-(2-methoxyphenyl)ethyl)perhydroisoindol-4-one; C078949:FK 888; C085215:SR 140333; D013373:Substance P; C066892:CP 96345