Ricin toxin

Ricin toxin is a highly potent cytotoxin and lectin produced in the seeds of the castor oil plant (Ricinus communis). It is a heterodimeric protein consisting of two chains: the A chain (RTA), an RNA N-glycosidase that enzymatically depurinates ribosomal RNA and irreversibly inhibits protein synthesis, and the B chain (RTB), a lectin that binds galactose-containing glycoproteins and facilitates entry of the toxin into cells. Upon cellular uptake by endocytosis, the A chain is released into the cytosol where it disables ribosomes and causes rapid cell death. Ricin is one of the most toxic naturally occurring substances and is classified as a type II ribosome-inactivating protein and a select agent due to its potential use as a biological weapon. There are currently no effective antidotes, and supportive care is the mainstay of treatment in cases of poisoning.

Other names

RicinRCARCA-IIRicinus communis agglutinin II

Inactivates ribosomes by depurinating a specific adenosine in the 28S rRNA, halting protein synthesis and leading to apoptosis/cell death