Single-chain ribosome-inactivating protein, possessing high antiviral potency and low toxicity to normal cells in culture and to intact animals. Capable of inhibiting HIV-1 infection and replication. Endohydrolysis of the N-glycosidic bond at one specific adenosine on the 28S rRNA. Belongs to the ribosome-inactivating protein family. Type 1 RIP subfamily.