Figure 7.

Conformational changes in the modulator binding site during agonist binding and clamshell closure. A, Shown here are α-carbon traces of the dimers from the Ani/FW complex and the apo state (Armstrong and Gouaux, 2000), in which the domain 1 from protomer B was superposed. In the boxed region, aniracetam is drawn, as are the side chain atoms for Pro 494 and Ser 497.B, Closeup view of the boxed region from A. The Ani/FW structure is blue, and the apo structure is gray. During agonist and modulator binding, the main chain atoms of residues Pro 494–Ser 497 move ∼1.5 Å into the modulator binding site.