The cholera toxin is an AB5-type toxin, comprising an enzymatic A subunit and a pentameric B subunit. The B subunit binds to GM1 gangliosides on the surface of intestinal epithelial cells, facilitating the entry of the A subunit into the cytoplasm. Once inside, the A subunit ADP-ribosylates the Gs protein, leading to the activation of adenylate cyclase and increased cyclic AMP levels. This cascade results in the secretion of electrolytes and water into the intestinal lumen, causing diarrhea.
