Diphtheria toxin entry: protein translocation in the reverse direction.

Abstract

Diphteria toxin is a protein that binds to cell surface receptors and then enters the cytosol, where it inactivates elongation factor 2, thus inhibiting protein synthesis. Translocation of the enzymatically active part of the toxin across the plasma membrane can be induced at low pH. Receptor molecules appear to be involved in the translocation process, which also requires an inwardly directed H+-gradient and permeant anions. Transient cation-selective channels are formed upon toxin entry.