Heat-labile enterotoxin family
It then acts by raising cAMP levels through ADP-ribosylation of the alpha-subunit of a Gs protein leading to the constitutive activation of adenylate cyclase.In addition to its effects on chloride secretion, which involve the same steps as the effects of cholera toxin, Elt binds additional substrates: lipopolysaccharide on the surface of E. coli cells and A-type blood antigens.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.Partial insertion sequences (ISs) flanking the elt genes provide extra transmission capabilities by homologous recombination at their inverted repeats.