Toxin entry and trafficking in mammalian cells.

There is a vast number of bacterial and plant toxins that affect cytosolic targets in mammalian cells, and whether the purpose of the toxin is to act as a defence mechanism against predators, or to cause deliberate cell death in order to form an environment more suitable for bacterial growth, each of these toxins must cross a lipid membrane barrier in order to exert their effect. This review looks at the methods employed by bacterial and plant toxins in order to reach their target. We examine the trafficking methods involved in toxin transport throughout the cell, highlighting the proteins necessary for the toxins movement, and noting how many of the toxins hijack the cells own trafficking and protein processing machinery in order to reach their goals. Studying the trafficking of toxins has led to a greater understanding of retrograde transport, a process which has key relevance to the correct intracellular delivery of pharmacological agents.