RT Journal Article
SR Electronic
T1 Identification of Essential Residues Involved in the Glutamate Binding Pocket of the Group II Metabotropic Glutamate Receptor
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 944
OP 954
DO 10.1124/mol.60.5.944
VO 60
IS 5
A1 Pari Malherbe
A1 Frédéric Knoflach
A1 Clemens Broger
A1 Serge Ohresser
A1 Claudia Kratzeisen
A1 Geo Adam
A1 Heinz Stadler
A1 John A. Kemp
A1 Vincent Mutel
YR 2001
UL http://molpharm.aspetjournals.org/content/60/5/944.abstract
AB Metabotropic glutamate (mGlu) receptors are a family of G-protein-coupled receptors that play central roles as modulators of both glutamatergic and other major neurotransmitter systems in CNS. Using molecular modeling, site-directed mutagenesis, [3H]LY354740 binding, [35S]GTPγS binding, and activation of GIRK current, we have been able to identify residues crucial for the binding of LY354740 and glutamate to rat mGlu2 receptors. Several of the crucial residues located in the binding site (Arg-57, Tyr-144, Tyr-216, Asp-295) have not been identified previously. We propose that the γ-carboxyl group of LY354740 forms H-bonds to Arg-57, whereas the α-carboxyl group forms an H-bond with the hydroxyl group of Ser-145. The α-amino group of LY354740 forms H-bonds to Asp-295 and to the side-chain hydroxyl group of Thr-168. In addition, Tyr-144 may establish a hydrophobic (C-H/π)–interaction with the bicyclo-hexane ring of LY354740. Furthermore, the mutation of residues Ser-148 and Arg-183, which are too remote for a direct interaction, affected the ligand affinity dramatically. These results suggest that Ser-148 and Arg-183 may be important for the 3D structure and/or are involved in closure of the domain. Finally, Asp-146, which is also remote from the binding site, was shown to be involved in the differential binding affinity of [3H]LY354740 for mGlu2 versus mGlu3 receptors. All the mGlu receptors except mGlu2 are activated by Ca2+ and have serine instead of aspartic acid at this position, which suggests a critical role of this aspartic acid residue in the binding properties of this unique receptor.