Structural model for the gating transition of the pore in Kv7.3 and the site of action of RTG.
A–F, homology models of the Kv7.3 PM in the closed (red, A and C) and open conformations (green, B and D; orange/green, E and F) built using the closed channel structure of KvLm (PDB code 4H33) (22) and open channel structure of Kv1.2-Kv2.1 (PDB code 2R9R) (37). The end view of a solvent-accessible surface map of the closed model (A) shows that the channel is occluded, whereas a similar depiction of the open channel model (B) delineates the presence of K+ in the permeation pathway, consistent with the passage of K+ (yellow, B) through the channel pore. Side views of a single subunit in the closed conformation (C) and in the open conformation (D) highlight predicted π-π interactions (black lines) in each monomer that delineate a change in the interaction partners when the channel gates open. E and F, two low-energy docking models of RTG onto the open channel module (side views), both involving a π-π interaction between Trp-265 and RTG, with amino acids forming the pocket (distance between protein and RTG, <5 Å) labeled explicitly.