Gelonin

Gelonin is a type 1 ribosome-inactivating protein and toxin of approximately 30 kDa found in the seeds of the Himalayan plant Gelonium multiflorum.

In cell-free systems gelonin exerts powerful N-glycosidase activity on the 28S rRNA unit of eukaryotic ribosomes by cleaving out adenine at the 4324 site.

Gelonin lacks carbohydrate-binding domains so it is unable to cross the plasma membrane, making it highly effective only in cell free systems.

This facilitates the cleavage of the glycoside bond connecting the nucleobase and ribose, creating a transition state with a positively charged oxocarbenium ion intermediate.

[7] Multiple gelonin delivery systems have been engineered, including conjugation to a cell-penetrating peptide,[8] liposome encapsulation using listeriolysin O,[7] and attachment to bispecific antibodies.