Crystal structure of human AQP1. The images were screen-printed from an open access database available at http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1FX8. The yellow circles correspond to carbon atoms within individual residues. The model was originally determined by Ren et al. (2000) at 3.70-Å resolution through electron crystallography of ice-embedded 2-D crystals.