Water in the α-Btx-bound non-conducting AChR channel pore. Water distribution along the pore of α-Btx-bound non-conducting channel (PDB ID: 6UWZ) observed for the last 20 ns of the unbiased simulation. The color scheme of M2 pore helices is the same as in Video 1. Red spheres: water (O atom). Bulk of the pore region (exceeding beyond 9′–16′ residues) was devoid of water molecules and remained resolutely shut throughout the observation duration. No water molecule could be seen crossing this constricted region. The α-Btx-bound state in AChRs (PDB ID: 6UWZ) was different from the closed state (PDB ID: 7QKO).
