Figure 6.

Representative AQP-inhibitor binding sites. A–C, the calculated diameter of the AQP pore is shown in transparent surface view, colored from blue (narrowest) to red (widest). Docked ligands and select amino acids are shown in stick representation. Hydrogen bonds form between the inhibitor urea linker and backbone carbonyls of each AQP isoform. Asparagines of the NPA boxes form interactions between AQP3 and DFP00173 (A) and between AQP7 and Z433927330 (B). Phe-180 is unique to AQP9 and may form a positive edge interaction with an RF03176 nitrogen lone pair, thereby stabilizing a conformation that constricts the entrance to the pore (C).