Pokeweed antiviral protein(PAP), isolated from leaves and seeds of Phytolacca americana, are single-chain ribosome-inactive proteins(RIPs) with molecular mass of 29 to 31KD, which can inhibit translation by catalytically removing a specific adenine residue from a highly conserved, surface-exposed, stem-loop structure in the large rRNA of eukaryotic and prokaryotic ribosomes. PAP displays broad-spectrum antiviral activity against a number of different viruses, including plant and animal viruses. The property...