Retro-translocation of proteins from the endoplasmic reticulum into the cytosol

Proteins that are misfolded in the endoplasmic reticulum are transported back into the cytosol for destruction by the proteasome. This retro-translocation pathway has been co-opted by certain viruses, and by plant and bacterial toxins. The mechanism of retro-translocation is still mysterious, but several aspects of this process are now being unravelled.