According to the literature, members of the structural domains which comprise this superfamily correspond to the structure the protein DotD, one of the core components of the Dot/Icm type IVB secretion system (T4BSS) which, as well as T4ASS, play a central role in pathogenesis. The T4BSS core complex spans the inner and outer membranes. It is thought to be comprised of at least five proteins: DotC, DotD, DotF, DotG and DotH, with the latter being the outer membrane protein. DotD, together with DotC, is thought to be involved in the targeting of DotH PMID:20949065