Ribosome-inactivating protein of type 1, inhibits protein synthesis in animal cells. Endohydrolysis of the N-glycosidic bond at one specific adenosine on the 28S rRNA. Appears to undergo proteolytic cleavage in the C-terminal to produce a shorter protein. Especially useful as immunotoxin for pharmacological applications as it has low toxicity in rats and mice but is potent once inside target cells. Belongs to the ribosome-inactivating protein family. Type 1 RIP subfamily.