Ribosome-inactivating Proteins (RIPs) are a group of cytotoxin proteins that usually contain a RNA N-glycosidase domain, which irreversibly inactivates ribosome, thus inhibiting protein synthesis. During the past 14 years (1990-2004), the studies conducted in our laboratory had been focusing on the
Cinnamomin, a type II ribosome-inactivating protein (RIP) isolated from the seeds of Camphora tree (Cinnamomum camphora), could not inactivate its own (autologous) ribosome. Among five RIPs (Cinnamomin A-chain, ricin A-chain, trichosanthin, gelonin, and soporin-S6) tested, only saporin-S6 could