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. Author manuscript; available in PMC: 2013 Mar 20.
Published in final edited form as: Biochemistry. 2012 Mar 7;51(11):2199–2212. doi: 10.1021/bi201888a

Figure 5. The size of the CFTR pore varies along the pore axis.

Figure 5

Plotted is the mean diameter of the largest circle that can be fitted inside the irregular pore cross-sections defined by castings of the 27 MD frames. The brown envelope represents the maximum and minimum values at each axial point. The tan shading in the background indicates the position of the lipid bilayer. Dashed horizontal lines show the diameter of three molecules known to pass through the CFTR pore: urea, chloride, and water (see text for more details). A representative frame of the casting (16 ns) is shown in gray above the plot. For orientation, amino acid side chains from TMs 6 and 12 are shown and colored based on their reactivity to both channel-permeant and channel-impermeant (red), or only channel-permeant (yellow) reagents. Amino acids shown here are those indicated in the cross-sectional slices of Figure 3.