Figure 3. Translocation channel of the PA pore.

a, Electrostatic surface (left) and channel radius profile (right; calculated with MOLE¹⁶) of the PA pore. An α helix (green surface model of residues 555–574 of LF; PDB ID: 1J7N) is modeled in the β barrel. The green arrow depicts the direction of protein translocation. b, The translocation channel (dots) running through the Φ-clamp. Two protomers of the PA pore are shown as ribbons. Residues E398, D425, D426, F427, and S429 (ball-and-stick) are exposed to the channel. c, d, Hydropathy surface of the PA pore (brown: hydrophobic; purple: hydrophilic; white: neutral). In c, the front half of the structure is removed to show the luminal surface. In d, two 1,2-dihexadecanoyl-sn-glycero-3-phosphocholine (DPPC) lipid molecules are modeled near the membrane insertion region. e, Bottom and side views of the segmented cryoEM map showing the β barrel (yellow) bound with disordered detergent molecules (grey). f, The 14-stranded β barrel (ribbons) and the hydrophobic residues (spheres) on its outer surface. The hydrophobic residues are depicted on different protomers for the ease of presentation.