Pertussis Toxin, Salt-Free

Pertussis toxin (PT/PTX) is a complex multisubunit protein toxin secreted by Bordetella pertussis, the bacterium responsible for the disease known as pertussis or whooping cough. This toxin isclassified as an AB5 protein, comprising an enzymatically active A subunit (S1) that is non-covalently linked to a pentamer of binding subunits (S2, S3, and twocopies of S4 and S5). PT functions by inhibiting G protein-coupled receptor signaling through Gi proteins in mammalian cells. This multimeric 105 kDa protein is one of the mostcomplex bacterial protein toxins. Due to its diverse biological activities, PTX was initially known by several names, including histamine-sensitizing factor, lymphocytosis-promoting factor, hemagglutinin, and islet-activating protein. The realization that these various activities stem from a single protein prompted Pittman to suggest the name ‘pertussis toxin’. PTX belongs to the family of ADP-ribosylating toxins. It plays a role in activating innate immuneresponses and modulating adaptive immune responses.