Endocytosis and retrograde transport of Shiga toxin.

Shiga toxin belongs to the group of bacterial and plant toxins that act on cells by binding to cell surface receptors via a binding-moiety, then the toxins are endocytosed and transported retrogradely to the Golgi apparatus and the endoplasmic reticulum (ER) before an enzymatically active moiety enters the cytosol and exerts the toxic effect. In the case of Shiga toxin, similarly to plant toxins such as ricin and viscumin, the toxin removes one adenine from the 28S RNA of the 60S subunit of the ribosome and thereby inhibits protein synthesis. This ribotoxic effect is in some cells followed by apoptosis. In this article we focus on new discoveries concerning endocytosis and retrograde transport of Shiga toxin to the Golgi, the ER and the cytosol.