hi in this video I will talk about the mechanism of cholera toxin and how cholera toxin interacts with g-protein signaling caused a huge amount of sweet loss from the body now cholera is caused by the bacterium vibrio cholerae and it results in huge amount of fluid loss diarrhea vomiting and dehydration now cholera gets transmitted by mainly by water which is contaminated with fecal matter or anything so the Vibrio cholerae infects the intestinal epithelial cells intestinal epithelial cells has chain one ganglia side receptors which actually binds to the cholera toxin and cholera toxin falls under the
classical category of a B top C it has two subunits once a B toxin binds to the gm1 receptor on the surface of intestinal epithelial cell it gets internalized and normally this heavy toxin interferes with g-protein signaling normally g-protein signaling is activated when G alpha subunits get dissociated from the G beta and gamma and activates adnan of cycles and this results in conversion of ATP to cyclic GMP and thus downstream signaling cascade goes on and on what cholera toxin does is the a subunit of the cholera toxin does a specific type of modification on G
alpha subunit which is adp ribosylation the cholera toxin takes adp-ribose group from nad and put it onto the G alpha subunit and as a result the G alpha subunit is locked into its own configuration that means the gtp-bound state since the G alpha subunit is locked into its own state now huge amount of psychic EMP would be produced and so the downstream signaling would be also also on for a long time this would result in huge amount of protein kinase a activation protein kinase a phosphorylates CFTR a chloride ion channel now opening of CFTR would
allow a huge amount of chloride ion loss now due to this a B toxin a huge amount of chloride ion is lost in the intestinal lumen to compensate for this also water is lost now water is lost from the intestinal epithelium and also from the blood vessels water is getting evacuated that means huge amount of water is going into the intestinal lumen and that is causing the huge amount of diarrhea and fluid loss from the body I hope you enjoyed this video if you like my video give it a thumbs up please don't forget to
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