FIG. 1.

(a) Front view of the simulation system, including water reservoirs, lipid bilayer, and an AQP tetramer. Single-file water chains are formed in AQP monomer (only one shown). (b) The channel radius averaged over 20 ns production run and the designation of NPA and ar/R regions. Coarse-grained cross-section of the channel representing the hourglass topology of the AQP channel is also shown. (c) Single-file water formation in the pore with illustration of cytoplasmic, extracellular, and pore constriction regions labeled.