| Autor: |
Hampson, David R., Huang, Xi-Ping, Pekhletski, Roman, Peltekova, Vanya, Hornby, Geoffrey, Thomsen, Christian, Thøgersen, Henning |
| Zdroj: |
Journal of Biological Chemistry; November 1999, Vol. 274 Issue: 47 p33488-33495, 8p |
| Abstrakt: |
Metabotropic glutamate receptors (mGluRs) are G-protein-coupled glutamate receptors that subserve a number of diverse functions in the central nervous system. The large extracellular amino-terminal domains (ATDs) of mGluRs are homologous to the periplasmic binding proteins in bacteria. In this study, a region in the ATD of the mGluR4 subtype of mGluR postulated to contain the ligand-binding pocket was explored by site-directed mutagenesis using a molecular model of the tertiary structure of the ATD as a guiding tool. Although the conversion of Arg78, Ser159, or Thr182to Ala did not affect the level of protein expression or cell-surface expression, all three mutations severely impaired the ability of the receptor to bind the agonist l-[3H]amino-4-phosphonobutyric acid. Mutation of other residues within or in close proximity to the proposed binding pocket produced either no effect (Ser157and Ser160) or a relatively modest effect (Ser181) on ligand affinity compared with the Arg78, Ser159, and Thr182mutations. Based on these experimental findings, together with information obtained from the model in which the glutamate analog l-serineO-phosphate (l-SOP) was “docked” into the binding pocket, we suggest that the hydroxyl groups on the side chains of Ser159and Thr182of mGluR4 form hydrogen bonds with the α-carboxyl and α-amino groups on l-SOP, respectively, whereas Arg78forms an electrostatic interaction with the acidic side chains of l-SOP or glutamate. The conservation of Arg78, Ser159, and Thr182in all members of the mGluR family indicates that these amino acids may be fundamental recognition motifs for the binding of agonists to this class of receptors. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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