Heat-labile enterotoxin, A chain (IPR001144)

Short name: Enterotoxin_A

Overlapping homologous superfamilies


Family relationships



Escherichia coli heat-labile enterotoxin is a bacterial protein toxin with an AB5 multimer structure, in which the B pentamer (IPR001835) has a membrane-binding function and the A chain is needed for enzymatic activity [PMID: 8478941]. The B subunits are arranged as a donut-shaped pentamer, each subunit participating in ~30 hydrogen bonds and 6 salt bridges with its two neighbours [PMID: 8478941].

The A subunit has a less well-defined secondary structure. It predominantly interacts with the pentamer via the C-terminal A2 fragment, which runs through the charged central pore of the B subunits. A putative catalytic residue in the A1 fragment (Glu112) lies close to a hydrophobic region, which packs two loops together. It is thought that this region might be important for catalysis and membrane translocation [PMID: 8478941].

GO terms

Biological Process

GO:0009405 pathogenesis

Molecular Function

GO:0090729 toxin activity

Cellular Component

GO:0005615 extracellular space

Contributing signatures

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