1. B. Physicochemical features of the AQP1 water channel
B. Physicochemical features of the AQP1 water channel. Three water molecules (purple) represent transient interactions with the pore-lining at discrete sites. Bulk water molecules (blue) occur in the extracellular and intracellular spaces. Three features of the channel make it selective for water. 1. The pore narrows 8 Å above the channel midpoint to a diameter of 2.8 Å. 2. At the narrowest region of the pore conserved residue (Arg-195) forms a barrier to cations, including protonated water (H3 O+). 3. Two short helixes meet at the channel midpoint, providing positively charged dipoles that reorient traversing water molecules, disrupting hydrogen bonding in the single-file chain of traversing water molecules and preventing the formation of proton conductance. (Adapted, with permission, from Kozono et al )
Source: The Blood–Brain Barrier, Choroid Plexus, and Cerebrospinal Fluid, Principles of Neural Science, Fifth Editon
Citation: Kandel ER, Schwartz JH, Jessell TM, Siegelbaum SA, Hudspeth AJ, Mack S. Principles of Neural Science, Fifth Editon; 2012 Available at: Accessed: January 01, 2018
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