Mode of entry into the cell - Receptor mediated endocytosis

Dimeric exotoxin binds to a receptor-ligand complex that is internalized in a clathrin-coated pit that pinches off to become a coated vesicle. By the time, the molecule A and B are cleaved at protease sensitive site, but remains covalantly associated. Clathrin coat depolymerizes resulting in an uncoated vesicle (endosome). pH in the endosome decreases owing to the AT activity by reduction of disulphide bond. Low pH causes A and B component to separate, which is called as CURL ( Compartment of Uncoupling of Receptor and Ligand ). B domain is then recycled to cell surface. A domain moves through the cytosol, and inhibits protein synthesis.