The neurokinin-1 and neurokinin-2 receptor binding sites of MDL103,392 differ.
Several small molecule non-peptide antagonists of the NK-1 and NK-2 receptors have been developed. Mutational analysis of the receptor protein sequence has led to the conclusion that the binding site for these non-peptide antagonists lies within the bundle created by transmembrane domains IV-VII of the receptor and differs from the binding sites of peptide agonists and antagonists. The current investigation uses site-directed mutagenesis of the NK-1 and NK-2 receptors to elucidate the amino acids that are important for binding and functional activity of the first potent dual NK-1/NK-2 antagonist MDL103,392. The amino acids found to be important for MDL103,392 binding to the NK-1 receptor are Gln-165, His-197, Leu-203, Ile-204, Phe-264, His-265 and Tyr-272. The amino acids found to be important for MDL103,392 binding to the NK-2 receptor are Gln-166, His-198, Tyr-266 and Tyr-289. While residues in transmembrane (TM) domains IV and V are important in both receptors (Gln-165/166 and His-197/198), residues in TM V and VI are more important for the NK-1 receptor and residues in TM VII play a more important role in the NK-2 receptor. These data are the first report of the analysis of the binding site of a dual tachykinin receptor antagonist and indicate that a single compound (MDL103,392) binds to each receptor in a different manner despite there being a high degree of homology in the transmembrane bundles. In addition, this is the first report in which a model for the binding of a non-peptide antagonist to the NK-2 receptor is proposed.
Greenfeder
S
S
Department of Allergy, Schering-Plough Research Institute, Kenilworth, NJ 07033, USA. scott.greenfeder@spcorp.com
Cheewatrakoolpong
B
B
Billah
M
M
Egan
R W
RW
Keene
E
E
Murgolo
N J
NJ
Anthes
J C
JC
D000818:Animals; D001665:Binding Sites / Q000235:genetics; D019556:COS Cells; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D064729:Neurokinin-1 Receptor Antagonists; D011487:Protein Conformation; D011758:Pyrroles / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D011759:Pyrrolidines / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D018040:Receptors, Neurokinin-1 / Q000235:genetics / Q000378:metabolism*; D018041:Receptors, Neurokinin-2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D014162:Transfection
C405340:MDL 103392; D064729:Neurokinin-1 Receptor Antagonists; D011758:Pyrroles; D011759:Pyrrolidines; D018040:Receptors, Neurokinin-1; D018041:Receptors, Neurokinin-2; D011994:Recombinant Proteins