Pertussis toxin (PT) is a protein-based exotoxin produced by the bacterium Bordetella pertussis.

Mechanism of pathogenesis

An A-B exotoxin, PT is released from B. pertussis in an inactive form. When the B subunit binds to a cell membrane receptor, the A subunit (or protomer) becomes activated, perhaps through the action of glutathione and ATP. PT catalyzes the ADP-ribosylation of the α subunits of the heterotrimeric guanine nucleotide regulatory proteins G_i, G_o, and G_t. This prevents the G-proteins from interacting with cell membrane receptors, thus interfering with intracellular communication. Since the Gα subunits remain in their GDP-bound, inactive state, they are unable to inactivate adenylyl cyclase or open potassium channels.

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