Abstract
Cys-loop receptor binding sites characteristically contain many aromatic amino acids. In nicotinic ACh and 5-HT3 receptors, a Trp residue forms a cation-pi interaction with the agonist, whereas in GABA(A) receptors, a Tyr performs this role. The glycine receptor binding site, however, contains predominantly Phe residues. Homology models suggest that two of these Phe side chains, Phe159 and Phe207, and possibly a third, Phe63, are positioned such that they could contribute to a cation-pi interaction with the primary amine of glycine. Here, we test this hypothesis by incorporation of a series of fluorinated Phe derivatives using unnatural amino acid mutagenesis. The data reveal a clear correlation between the glycine EC(50) value and the cation-pi binding ability of the fluorinated Phe derivatives at position 159, but not at positions 207 or 63, indicating a single cation-pi interaction between glycine and Phe159. The data thus provide an anchor point for locating glycine in its binding site, and demonstrate for the first time a cation-pi interaction between Phe and a neurotransmitter.
| Original language | English |
|---|---|
| Journal | The Journal of neuroscience : the official journal of the Society for Neuroscience |
| Volume | 28 |
| Issue number | 43 |
| Pages (from-to) | 10937-42 |
| Number of pages | 6 |
| ISSN | 0270-6474 |
| DOIs | |
| Publication status | Published - 22 Oct 2008 |
Keywords
- Amino Acids, Aromatic
- Animals
- Binding Sites
- Cations
- Glycine
- Humans
- Microinjections
- Models, Molecular
- Mutagenesis, Site-Directed
- Oocytes
- Phenylalanine
- Protein Binding
- Protein Conformation
- Protein Structure, Secondary
- Radioligand Assay
- Receptors, Glycine
- Structure-Activity Relationship
- Xenopus laevis