Cholera toxin subunit B (CTB)

Cholera toxin subunit B is the pentameric receptor-binding component of the AB5 holotoxin produced by Vibrio cholerae. Each B subunit (∼11 kDa) forms a doughnut-shaped pentamer that binds specifically and with high affinity to GM1 ganglioside receptors on the surface of intestinal epithelial cells[2][5]. This binding is necessary for the uptake and retrograde transport of the toxic A subunit, ultimately leading to the characteristic increase in cAMP and secretory diarrhea of cholera. CTB alone is non-toxic (lacking enzymatic activity), but it is highly immunogenic and has been widely used as a mucosal immune response stimulator, research tool for membrane trafficking, and as a carrier protein in chimeric vaccine development[1][4]. GM1 binding capacity and pentameric assembly are critical for its biological function[2].

Other names

Cholera enterotoxin subunit BCholera toxin B subunitCTB

Binds with high specificity to GM1 ganglioside on intestinal epithelial cells; mediates endocytosis and retrograde trafficking of the A subunit, enabling delivery of cytotoxic component[2][5]