Type II/III secretion system (IPR004846)

Short name: T2SS/T3SS

Overlapping homologous superfamilies


Family relationships


This family includes: protein D that is involved in the general (type II) secretion pathway (GSP) within Gram-negative bacteria, a signal sequence-dependent process responsible for protein export [PMID: 8438237, PMID: 1365398, PMID: 1592799,PMID: 8326859, PMID: 7901733, PMID: 7934814, PMID: 8190064] and protein G from the type III secretion system.

A number of proteins are involved in the GSP; one of these is known as protein D (GSPD protein), the most probable location of which is the outer membrane [PMID: 2677007]. This suggests that protein D constitutes the apparatus of the accessory mechanism, and is thus involved in transporting exoproteins from the periplasm, across the outer membrane, to the extracellular environment.

The type III secretion system is of great interest, as it is used to transport virulence factors from the pathogen directly into the host cell and is only triggered when the bacterium comes into close contact with the host. The protein subunits of the system are very similar to those of bacterial flagellar biosynthesis. However, while the latter forms a ring structure to allow secretion of flagellin and is an integral part of the flagellum itself [PMID: 10564516], type III subunits in the outer membrane translocate secreted proteins through a channel-like structure. Protein G aids in the structural assembly of the invasion complex [PMID: 8733226].

GO terms

Biological Process

GO:0009306 protein secretion

Molecular Function

No terms assigned in this category.

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.