Fig. 1.

Crystal structures of AMPA receptor ligand-binding domain (GluR2-S1S2) showing the dimer interface. The structures are (A) in the Apo state, (B) in the glutamate-bound state, (C) glutamate-bound in the presence of cyclothiazide, and (D) the S729C structure thought to represent the desensitized dimer interface. Residue 740 (741 in GluR4) in GluR2-S1S2, which was tagged with the donor:acceptor fluorophore in the LRET measurements, is highlighted as spheres, and the linker region where the transmembrane segments are attached is shown in magenta. All the structures show an intact dimer interface; the only structure that is different in terms of the interface, D, is shown in the GluR2-S1S2-S729C structure.