Protein toxins from plants and bacteria: Probes for intracellular transport and tools in medicine

A number of protein toxins produced by bacteria and plants enter eukaryotic cells and inhibit protein synthesis enzymatically. These toxins include the plant toxin ricin and the bacterial toxin Shiga toxin, which we will focus on in this article. Although a threat to human health, toxins are valuable tools to discover and characterize cellular processes such as endocytosis and intracellular transport. Bacterial infections associated with toxin production are a problem worldwide. Increased knowledge about toxins is important to prevent and treat these diseases in an optimal way. Interestingly, toxins can be used for diagnosis and treatment of cancer.