The resting (closed) and open-like conformations derived from the crystal structure of MscS. The entire crystal structure of MscS (pdb 1mxm) shown as a diminished side view (A) and a view from the top (D) presented in the same scale as other models. The transmembrane barrel of MscS in the closed state (B and E), and expanded open-like state (C and F) obtained through extrapolations. Domain colors: TM1 (gold), TM2 (green), TM3a (teal), TM3b (blue and dark blue), reconstructed N-terminal segments (red). The bottom row shows the models in the same scale to illustrate the degree of compaction of the resting state relative to the splayed crystal structure and the expansion associated with opening. In the extrapolated open state (C and F) the gate-keeping leucines (yellow WdV spheres) protrude directly into the pore.