| Abstract: | We have studied on the mechanism of ricin action on rat liver ribosomes and present evidence which shows that the toxin inactivates ribosomes by modifying two bases at positions G-4323 and A-4324 of 28S rRNA adjacent to alpha-sarcin cleavage site. Further results showing that those phosphodiester bonds are very labile against alkaline digestion and aniline-treatment strongly suggest that these purine bases are removed by N-glycosidase activity of the toxin. In parallel, we also present evidence showing that abrin and modeccin have the same activity on eukaryotic ribosomes as ricin does. |
