Outer membrane channel, which is required for the function of several efflux systems (By similarity). Required for virulence. Homotrimer. Part of tripartite efflux systems, which are composed of an inner membrane transporter, a periplasmic membrane fusion protein, and an outer membrane component, TolC. The complexes form a large protein conduit and can translocate molecules across both the inner and outer membranes (By similarity). Constitutively expressed (at protein level). Non-invasive for a number of mammalian cell lines; avirulent by oral infection of BALB/c mice. Increased sensitivity to acridine orange and novibiocin. Decreased resistance to bile salts and SDS. Belongs to the outer membrane factor (OMF) (TC 1.B.17) family.