Molecular mechanism of inhibition of mammalian protein synthesis by some four-chain agglutinins. Proposal of an extended classification of plant ribosome-inactivating proteins (rRNA N-glycosidases).

The four chain agglutinins from Abrus precatorius, Viscum album and Ricinus communis promote depurination of the 28 S rRNA from rabbit reticulocyte ribosomes characteristic of the common ribosome-inactivating proteins (RIPs). These agglutinins inhibited mammalian protein synthesis at nanomolar concentrations but they do not affect plant protein synthesis under the same conditions. Therefore, they should also be considered as true RIPs but of a new class, the four-chain RIPs. An extended classification of RIPs is presented based on the former one from Stirpe et al. [Bio/technology 10 (1992) 405-412].