Which of the following is TRUE about cholera toxin?
V cholerae produce a heat-labile enterotoxin. Ganglioside GM1 serves as the mucosal receptor for subunit B, which promotes entry of subunit A into the cell. Cholera toxin catalyzes the ADP ribosylation of the G protein, rendering it unable to dissociate from the active adenylate cyclase complex. This causes persistent activation of intracellular adenylate cyclase, which in turn stimulates the conversion of adenosine triphosphate to cAMP. The net effect is excessive accumulation of cAMP at the cell membrane, which causes hypersecretion of chloride, potassium, bicarbonate, and associated water molecules out of the cell. Ref: Brooks G.F. (2013). Chapter 17. Vibrios, Campylobacters, Helicobacter, and Associated Bacteria. In G.F. Brooks (Ed), Jawetz, Melnick, & Adelberg's Medical Microbiology, 26e.
Increases the levels of intracellular cyclic GMP
Acts through the receptor the opiates
Causes continued activation of adenylate cyclase
Inhibits the enzyme phosphodiesterase