Channel gating in tetrameric cation channels occurs as structural transitions that involve straightening and bending of inner helices at a conserved glycine residue. Structural representatives of these closed and opened states have come from crystal structure of KcsA and MthK, respectively. The structure of NaK in the open state, when combined with a previously determined structure of NaK in the closed state, allows the detailed analysis of channel gating within the same channel.
