Pertussis toxin they are formed from two subunits. The "A" subunit possesses enzyme activity, and is transferred to the host cell following a conformational change in the membrane-bound transport "B" subunit. Pertussis toxin is an exotoxin with six subunits (named "S1" through "S5"—each complex contains two copies of "S4"). The subunits are arranged in "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. The subunits are encoded by "ptx" genes encoded on a large PT operon that also includes additional genes
Riggs' disease Riggs himself. Riggs' disease Riggs' disease, also known as pyorrhea of a toothsocket or gingivitis expulsiva, is a historical term for periodontitis (gum disease), The condition was described as a purulent inflammation of the dental periosteum. It was named after American dentist John Mankey Riggs (1811–1885). Riggs' disease was said to produce the progressive necrosis of the alveoli and looseness of the teeth. The teeth may become very loose and fall out of the sockets. Mark Twain wrote briefly about Riggs' disease in his short essay, "Happy Memories of the Dental Chair", in which he claims to have been examined