Cholera toxin

Cholera toxin is a protein produced by the bacterium Vibrio cholerae. It disrupts signaling in intestinal cells, causing them to secrete electrolytes and water into the gut.

AB5 toxin: A toxin architecture with one enzymatic A subunit associated with a pentameric B subunit. Cholera toxin is a classic AB5 toxin: its B pentamer binds cells while its A subunit alters signaling.
Vibrio cholerae: A curved, motile bacterium that can cause cholera after colonizing the small intestine. This bacterium produces cholera toxin during intestinal infection.
Cholera toxin B subunit vaccine: A vaccine formulation containing the cholera toxin B subunit as a non-toxic antigen. The B subunit can induce antibodies that block toxin binding to intestinal cells.
Heat-labile enterotoxin: An enterotoxin produced by some Escherichia coli strains that closely resembles cholera toxin in structure and action. It uses a similar AB5 architecture and signaling mechanism but is produced by enterotoxigenic E. coli.
Ganglioside GM1: A glycolipid on cell membranes that serves as a receptor for several bacterial toxins. Cholera toxin’s B subunits bind GM1 on intestinal epithelial cells to enable uptake.
Cholera toxin B subunit: The receptor-binding component of cholera toxin, formed by five identical subunits. Its pentamer binds GM1 and helps deliver the toxin’s catalytic component into cells.
CTB as a research tool: The use of cholera toxin B subunit to label or study cells that display GM1. Its strong GM1 binding makes the B subunit useful for tracing membrane domains and cellular uptake.
Pertussis toxin: An AB5 toxin from Bordetella pertussis that ADP-ribosylates inhibitory G proteins. Unlike cholera toxin’s effect on stimulatory Gs, it disrupts Gi signaling.
ADP-ribosylation: A reaction that transfers an ADP-ribose group from NAD⁺ to a target molecule. The toxin’s A1 fragment ADP-ribosylates a G protein that regulates adenylate cyclase.
Cholera toxin A subunit: The catalytic component of cholera toxin, consisting of A1 and A2 segments. Its A1 segment modifies Gs alpha, while A2 helps connect it to the B pentamer.

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