Elderberry (Sambucus nigra) contains truncated Neu5Ac(α‐2,6)Gal/GalNAc‐binding type 2 ribosome‐inactivating proteins

Analysis of affinity‐purified preparations of the fetuin‐binding proteins from elderberry bark and fruits revealed besides the previously reported Neu5Ac(α‐2,6)Gal/GalNAc‐specific type 2 ribosome‐inactivating proteins (RIP) the occurrence of single chain proteins of 22 kDa, which according to their N‐terminal amino acid sequence correspond to the second part of the B chain of the respective type 2 RIP. Both proteins are very similar except that the polypeptides of the fruit lectin are 10 amino acid residues longer than these from the bark lectin. Our findings not only demonstrate the occurrence of carbohydrate‐binding fragments of type 2 RIP but also provide further evidence that type 2 RIP genes give rise to complex mixtures of type 2 RIP/lectins in elderberry.