In the small intestine, cholera toxin acts by:
A. ADP-ribosylation of the G regulatory protein
B. Inhibition of adenyl cyclase
C. Activation of GTPase
D. Active absorption of NaCl
Correct answer : A. ADP-ribosylation of the G regulatory protein
Cholera toxin increases adenyl cyclase activity by irreversible ADP ribosylation of GTP binding domain of adenyl cyclase.