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Pertussis toxinPertussis toxin (PT) is a protein-based AB5-type exotoxin produced by the bacterium Bordetella pertussis.[1] PT is involved in the colonization of the respiratory tract and the establishment of infection. Research suggests PT may have a therapeutic role in treating a number of common human ailments including hypertension,[2] viral inhibition,[3] and autoimmune inhibition.[4] Additional recommended knowledgeMechanism of pathogenesisPT is an exotoxin with six subunits (named S1 through S5—each complex contains two copies of S4).[5] The subunits are arranged in a A-B structure: the A component is enzymatically active and is formed from the S1 subunit, while the B component is the receptor-binding portion and is made up of subunits S2–S5.[5] The subunits are encoded by ptx genes encoded on a large PT operon that also includes additional genes which encode Ptl proteins: Together these proteins form the PT secretion complex.[6] 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.[7] PT catalyzes the ADP-ribosylation of the α subunits of the heterotrimeric G proteins Gi, Go, and Gt. This prevents the G proteins from interacting with G protein-coupled receptors on the cell membrane, thus interfering with intracellular communication.[8] Since the Gα subunits remain in their GDP-bound, inactive state, they are unable to inhibit adenylyl cyclase or open potassium channels. References
Categories: Signal transduction | AB5 toxins |
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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Pertussis_toxin". A list of authors is available in Wikipedia. |