FIG 3.

Structural alignment of the ligand-binding domains of PctA, PctB, and PctC. (A) Alignment of all six structures. PctA-LBD, shades of blue; PctB-LBD, shades of green; PctC-LBD, pink. (B and C) Expanded view of the binding pockets of PctA-LBD and PctB-LBD, respectively, containing different ligands. (D) Expanded view of the superimposed binding pockets of the three paralogous receptors. (E) Position of l-Ile, l-Gln, and GABA in the superposition of the three LBDs. The ligand carbon color corresponds to that of the corresponding protein chain.