Sec-independent protein translocase protein TatA/E (IPR006312)

Short name: TatA/E

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.

TatA and TatE are highly related proteins and appear to overlap in functionality [PMID: 9649434]. Translocation occurred in single mutants of either TatA or TatE, though much less efficiently, but double mutants showed no detectable translocation.

GO terms

Biological Process

GO:0009306 protein secretion
GO:0015031 protein transport

Molecular Function

GO:0008565 protein transporter activity

Cellular Component

GO:0016021 integral component of membrane
GO:0005886 plasma membrane

Contributing signatures

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