text: << 2-Amino-3-[3-hydroxy-5-(2-thiazolyl)-4-isoxazolyl]propionic acid >> (1) is a potent [[ AMPA receptor ]] agonist with moderate affinity for native kainic acid (KA) receptors, whereas (S)-E-4-(2,2-dimethylpropylidene)glutamic acid (3) show high affinity for the GluR5 subtype of KA receptors and much lower affinity for the GluR2 subtype of AMPA receptors.