Ligand binding to porcine ionotropic glutamate receptors with chemically modified arginyl residues

The involvement of arginyl residues in the binding of ligands to different ionotropic glutamate receptors, to the modulatory glycine site in the N-methyl-D-aspartate (NMDA) receptor and to the NMDA-governed ionophore was assessed with porcine cortical synaptic membranes. The arginyl residues were covalently modified with phenylglyoxal. The binding and protection experiments showed that arginine residue(s) are directly involved in the binding of ligands to the agonist sites of all ionotropic glutamate receptors and to the modulatory glycine site but not to the ion channel in the NMDA receptor complex.