A highly toxic protein, which exhibits similar effects to ribosome inactivating proteins (RIPs type II), isolated from Abrus pulchellus seeds kills mice in a few hours after injection in the peritoneal cavity (MV Ramos et al. 1998a Toxicon 36: 477-484). It is well documented in the literature that some toxins mediate their incursion by recognizing glycoconjugates on the cell surface membrane before translation. Plant and microbial toxins have been studied in detail mainly to understand their intrinsic toxic pathway. However, the toxin recognition mechanism by membrane receptors and its translation
through the membrane is poorly investigated, excepting abrin, the most investigated plant toxin. It has been determined that the initial recognition step must be mediated by carbohydrate-protein
interaction. The ribosome inactivating protein from the seeds of Viscum album is a typical protein of this class and its carbohydrate-binding specificity was carefully investigated (H Debray et al. 1994 Glycoconjugate J 11: 550-557). Although the RIPs type II are commonly specific for galactose residues, more complex carbohydrates are distinctly recognized.
