This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
[{'content': 'Peusis toxin acts by all of the following mechanisms except ? \nSelect and explain. \nA. ADP ribosylation of proteins associated with receptors, B. Increase cyclic AMP, C. Increased calcium release from sarcoplasmic reticulum, D. Acts through G alpha subunit', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., Increased calcium release from saroplasmic reticulum Peusis toxin . Peussis toxin is an exotoxin that has A and B subunits. . B subunit binds to the target cells whereas A subunit acts on the target. . First, the peussis toxin itself gets activated by glutathione and ATP. . Once the toxin gets activated it activates cell membrane bound G proteins. . Peussis toxin catalyzes the ADP ribosylation of the G proteins and activates them. . The activated G protein in turn activates adenylate cyclase, this results in an outpouring of cAMP which activates protein kinase and other intracellular messangers.", 'role': 'assistant'}]