Figure 7.
The Glu723 side chain undergoes a conformational switch. Fo-Fc omit electron density maps calculated using data to 1.87 and 2.11 Å for the GluR5 UBP302 (A) and the GluR5 glutamate (B) complexes contoured at 3.1 and 3.2 σ, respectively; atoms for Glu723, W7 and W8, and Asp745 through Tyr749 were omitted from the Fc calculation. Hydrogen bonds are shown by dashed lines. The UBP302 and glutamate ligands are drawn as yellow stick models. In the UBP302 structure, the Glu723 side chain was refined in two conformations: the first with 65% occupancy, makes a hydrogen bond with the side chain of Lys747, and the second, refined with 35% occupancy, is shown as a transparent stick figure and projects toward but does contact the ligand. In contrast, in the glutamate complex, the Glu723 side chain makes a hydrogen bond contact with the ligand α-amino group. Glu, Glutamate.