Heat-labile enterotoxin B subunit of Escherichia coli (LT-B)

The heat-labile enterotoxin B subunit of Escherichia coli (LT-B) is the pentameric cell-binding component of the AB₅ enterotoxin complex secreted by enterotoxigenic E. coli[1][2][3][4][5][7][8][9]. LT-B forms a highly stable, donut-shaped pentamer that binds with high affinity to GM1-ganglioside receptors on the plasma membrane of mammalian cells, mediating endocytosis and facilitating the entry of the catalytic A subunit, which then raises cAMP to induce watery diarrhea[1][3][5][7][9]. The B subunit itself is nontoxic, but is widely studied for its immunomodulatory properties—including induction of regulatory T cells, immune tolerance, and use as a potent mucosal adjuvant in experimental vaccines[5][7][9]. LT-B is antigenically related to the B subunit of cholera toxin, but distinct by sequence and immunogenicity[3][5]. The gene encoding LT-B is eltB, and its protein structure, function, and ability to modulate host-pathogen interactions are well characterized[2][4][6].

Other names

LT-BEtxBHeat-labile enterotoxin B chaineltBltpBLTP-B

Binds to GM1-ganglioside receptors on mammalian cells, enabling endocytosis and delivery of the catalytic A subunit[7][9]. - As a vaccine adjuvant, enhances immune response by promoting antigen uptake and modulating T cell activity[5][9].