Fig. 1.

Channels with extracellular and intracellular ends. Tunnels suitable for chloride conductance were identified in one case out of 22 equilibrium simulations with the ATP-bound CFTR structure (PDBID: 5W81) using Caver. The channels with top scores (spheres with red colors) were clustered based on the atom positions of the channel-lining residues. Intracellular residues with positive charges at the TM4/6 entry site are labeled with blue sticks. Lasso/L0 region, TMD1, TMD2, NBD1, and NBD2 domains are marked with dark green, pale green, green, yellow, and orange, respectively. Lipid molecules lining the pore in the region of TM8 are shown by black sticks. a, b Side views from the bilayer hydrophobic core. c A top view from the extracellular space