FIGURE 1.

GAT-2-GABA models and their validation by ligand enrichment. A and B, predicted structures of the GAT-2-GABA complex in the occluded (A) and the outward facing (B) conformations. GABA is colored in cyan, with oxygen, nitrogen, and hydrogen atoms in red, blue, and white, respectively. The sodium ions Na1 and Na2 are visualized as purple spheres. The transmembrane helices of GAT-2 are depicted as white ribbons. Key residues are displayed as sticks. The hydrogen bonds between GABA and GAT-2 are shown as dotted gray lines; they involve the residues Glu-48, Gly-51, and Gly-53, as well as the sodium ion Na1 for both conformations models. GABA forms polar interactions with Asn-54 only in the occluded conformation model. C and D, enrichment plots for different structures of the occluded (C) and the outward facing (D) models: the refined GAT-2 models (blue), random selection (red), the initial GAT-2 models (green), and the LeuT template structures (orange).