ABSTRACT
Ricin is a highly toxic plant protein produced by the seeds of the castor plant. It belongs to the ribosome inactivat-ing proteins(RIP)family and causes cell death by inhibiting the protein synthesis activity of ribosome. Ricin takes a unique pathway calledretrograde trafficking pathwayto enter the cytosol,where it interacts with ribosome and then exerts its inhibitory activity. No effective antidote agents have been developed for the treatment of ricin poisoning. In this paper,the structure,cell trafficking process, toxicological mechanism and the research progress in ricin antitoxin agents are reviewed.
ABSTRACT
Ricin is a plant toxin isolated from the seed of the castor plant(Ricinus communis). As a typical II ribosome inactivating protein,ricin consists of two polypeptide chains named ricin toxin A chain(RTA)and ricin toxin B chain(RTB),linked via a disulfide bridge. RTB binds to both glycopro?tein and glycolipid at the surface of the target cell and mediates ricin to be endocytosed and transported retro?gradely to the endoplasmic reticulum. After being reduced and retrotranslocated to the cytosol,RTA mediates its toxicity due to its activity of a RNA N- glycosidases. Aside from its main toxic effect of protein synthesis inhibition,ricin also displays other properties that contribute to its toxicity such as inducing apoptosis,cytokine secreting and peroxidation. Ricin is stable and can be easily isolated. It has many routes of intoxication with no specific antidotes. Due to its natural abundance,remarkable toxicity,and the potential to be used in biological warfare as well as terrorist attacks,ricin has been classified as a Category B biothreat agent. Here we reviewed its history as a biothreat agent,constitu?tion,intoxication mechanism,detection methods and the development of specific antitodes.