The M ring may be actively involved in energy transduction. The basal body constitutes a major portion of the flagellar organelle and consists of four rings (L,P,S, and M) mounted on a central rod. The M ring is integral to the inner membrane of the cell and may be connected to the flagellar rod via the S ring. The S (supramembrane ring) lies just distal to the M ring. The L and P rings lie in the outer membrane and the periplasmic space, respectively. Belongs to the FliF family.