Activities associated with the presence of ribosome‐inactivating proteins increase in senescent and stressed leaves

Abstract

The ribosome-inactivating proteins (RIPs) from Hura crepitans and Phytolacca americana release adenine from herring sperm DNA. Leaf extracts from these plants show the same enzymatic activities as the RIPs. The translation inhibitory activity and the activity on DNA are both increased in the leaves of both plants during senescence or when subjected to heat or osmotic stress. It is proposed that a physiological role of RIPs could be to intervene in the death of plant cells.