“…The tetranucleotides GAGA, at the apex of the singlestranded loop of the sarcin domain, form the site at which the ribosome-inactivating protein acts [4,10,11,32,43,44]. On the other hand, despite several genes of ribosomeinactivating proteins having been determined [15,18,24,33,42], the structure of the ribosome-inactivating protein that participates in catalyzing the hydrolysis of ribosomes or ribonucleic acids has not been completely revealed yet. Elucidation of the action of ribosome-inactivating protein on its substrates has been attempted using genetic manipulation, with limited success, however, because of the lethality of the protein-inactivating protein to the host cells [19,22,23,45].…”