Ricin is highly toxic to animal cells, and to a lesser extent to plant cells.; [Ricin A chain]: Acts as a glycosidase that removes a specific adenine residue from an exposed loop of the 28S rRNA (A4324 in mammals), leading to rRNA breakage. As this loop is involved in elongation factor binding, modified ribosomes are catalytically inactive and unable to support protein synthesis. Can inactivate a few thousand ribosomes per minute, faster than the cell can make new ones. Therefore a single molecule can kill an animal cell.; [Ricin B chain]: Binds to beta-D-galactopyranoside moieties on cell surface glycoproteins and glycolipids and facilitates the entry into the cell of the A chain. Also responsible for cell agglutination (Lectin activity).

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