Fig 1. Overview of the bacterial flagellar motor complex and the MS-ring.

(A) Schematic of bacterium flagellar motor. The soluble region of the MS-ring, sometimes called the S-ring, is shown in blue while the membrane-spanning region of the MS-ring, sometimes called the M-ring, is shown in magenta. Both the M-ring and S-ring are formed from FliF subunits. The switch complex, or C-ring, is shown in purple and contains FliG, FliM and FliN. (B) Linear schematic of the FliF protein sequence with the transmembrane regions colored magenta, RBM1 colored cyan, RBM2 colored yellow, RBM3a and RBM3b colored blue, the β-collar regions colored orange, and the cytosolic regions and linkers colored grey.