Fig. 4

A tethered plug motif in SsTRIC channel. a Occlusion of the cytoplasmic vestibule by the plug motif. The sectional view of the surface model of SsTRIC structure shows the position of plug motif inside the cytoplasmic vestibule. b The plug motif tethered in the loop region between M5 and M6 helices. The plug motif is highlighted in yellow, and the basic residues are shown as stick models colored in cyan (Lys) or green (Arg). The magenta elliptical rings define an array of three basic residues nearby the plug motif. c The Velcro-like interactions between the plug motif and the potential voltage-sensing basic residues. Green dashed lines indicate the hydrogen bonds or ionic interactions between two adjacent residues. Bond lengths (Å) are labeled nearby the dashed lines. d A model of SsTRIC with plug motif dislocated or removed. For comparison, the view is identical to the one shown in a. The cytoplasmic vestibule appears much wider and extends closer toward the bottom of extracellular vestibule. The dashed line denotes the mobilized plug motif at an unknown position