Twin-arginine translocation protein TatB (IPR018448)

Short name: TatB

Overlapping homologous superfamilies


Family relationships


Translocation of proteins across the two membranes of Gram-negative bacteria can be carried out via a number of routes. Most proteins marked for export carry a secretion signal at their N terminus, and are secreted by the general secretory pathway. The signal peptide is cleaved as they pass through the outer membrane. Other secretion systems include the type III system found in a select group of Gram-negative plant and animal pathogens, and the CagA system of Helicobacter pylori [PMID: 9649434].

In some bacterial species, however, there exists a system that operates independently of the Sec pathway [PMID: 10652088]. It selectively translocates periplasmic-bound molecules that are synthesised with, or are in close association with, "partner" proteins bearing an (S/T)RRXFLK twin arginine motif at the N terminus. The pathway is therefore termed the Twin-Arginine Translocation or TAT system. Surprisingly, the four components that make up the TAT system are structurally and mechanistically related to a pH-dependent import system in plant chloroplast thylakoid membranes [PMID: 10652088]. The gene products responsible for the Sec-independent pathway are called TatA, TatB, TatC and TatE.

TatB is essential for the secretion of these specific proteins, and forms a scaffold upon which TatC assembles in the membrane. Deletion studies have shown that it is crucial in the forming of the TAT complex, and is therefore necessary for the correct working of the system.

GO terms

Biological Process

GO:0043953 protein transport by the Tat complex

Molecular Function

No terms assigned in this category.

Cellular Component

GO:0016020 membrane

Contributing signatures

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