What is the mechanism of action of cholera toxin in the small intestine?
Correct Answer: ADP-ribosylation of the G regulatory protein
Description: Cholera toxin is an example of A-B model of toxins. B subunit of the toxin binds to the enterocyte receptors, active toxin subunit A activates adenylate cyclase of the intestinal epithelial cells by ADP ribosylation of the Gs subunit of the G protein of intestinal cells. This prevents the G protein from being turned off, and result in excess production of cAMP. cAMP in turn act as a second messenger to activate protein kinase A, which intern activates the specific cell proteins that control secretion of electrolytes. Ref: Textbook of Pathology By V. Krishna, Page 178; Medical Microbiology By Fritz H. Kayse, Page 298; Microbiology and immunology By Monica Gandhi, Page 45
Category:
Microbiology
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