Peusis toxin acts by all of the following mechanisms except ?
ADP ribosylation of proteins associated with receptors
Increase cyclic AMP
Increased calcium release from sarcoplasmic reticulum
Acts through G alpha subunit
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.