(A) Crystal structure of GLIC in a presumed open state (PDB ID 3EHZ). Histidines studied here are highlighted.
(B) Top-down overlay of a locally closed GLIC mutant structure (blue, PDB ID 3TLU) with the open channel structure (green), omitting the extracellular domain. Note the movement of the M2 helix associated with channel opening.
(C) Side view overlay of locally closed (blue) and open (green) GLIC structures. The orientation of the depicted residues suggests the formation of a hydrogen bond (dashed line) between His234 and the backbone carbonyl of I258 upon channel activation.