Ordinarily, dangerous proteins taken up by the cell are routed via a cellular compartment called the endosome to the lysosome, where they're destroyed. Shiga toxin, however, escapes this path by leaving the endosome, hitchhiking on a cellular protein, and traveling to the endoplasmic reticulum (the cell's protein production machinery, and on to the cell’s watery interior). Once there, the toxin halts protein production and kills the cell.
Pictured here, Shiga toxin (green) is sorted from the endosome into membrane tubules (red), which then pinch off and move to the Golgi apparatus.
