Diphtheria toxin exerts its cytotoxic effect by which of the following mechanisms?
- A Inhibits protein synthesis by ADP-ribosylation of elongation factor-2 ✓
- B Inhibits acetylcholine release at the neuromuscular junction
- C Activates adenylate cyclase by ADP-ribosylation of Gs protein
- D Lyses cell membranes by forming transmembrane pores
Correct answer: A. Inhibits protein synthesis by ADP-ribosylation of elongation factor-2
Explanation
Diphtheria toxin is an exotoxin that enters cells and catalyzes the ADP-ribosylation of elongation factor-2, blocking protein synthesis and causing cell death. Botulinum toxin inhibits acetylcholine release. Cholera toxin activates adenylate cyclase. Pore-forming toxins are used by other bacteria like Staphylococcus aureus.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.