Abrin lectin

In addition to the aforementioned effects on paracellular drug transport, Ca2+ also plays an important role in the transcytosis of macromolecules. The entry of the plant lectins abrin, modeccin, and viscumin into Vero cells was inhibited in a Ca2+-free medium a well as in a Ca2+-containing medium containing verapamil and Co2+, both inhibitors of Ca2+ [217], Ca2+ is therefore required at a stage after the binding of the above lectins, perhaps in the fusion and exocytosis of membrane vesicles. 

Abrus Abrins (toxic lectins) Abrus precatorius, A. pulchellus Apoptotic (Gal-specific lectin)... 

Fodstad, O., Olsnes, S., Pihl, A. (1976). Toxicity, distribution and elimination of the cancerostatic lectins abrin and ricin after parenteral injection into mice. Br. J. Cancer 34 418-25. Fodstad, O., Johannessen, J.V., Schjerven, L., Pihl, A. (1979). Toxicity of abrin and ricin in mice and dogs. J. Toxicol. Environ. Health 5 1073-84. 

Olsnes, S., Refsnes, K., Pihl, A. (1974b). Mechanism of action of the toxic lectins abrin and ricin. Nature 249 627-31. 

Chemical Abstracts Service Registry Number CAS 1393-62-0. Abrin is a toxalbumin similar in structure, absorption, and mechanism of action to ricin but is found not in castor beans but rather in jequirity beans. No reports of its use as a battlefield or terrorist agent exist, but in mice it is 75 times more potent than ricin. No specific treatment is available. Both ricin and abrin are type 2 ribosomal inhibitory proteins (RIPs) the other potent toxins in this class are Eranthis hyemalis lectin (EHL) from winter aconite, modeccin and volkensin from African succulents, and viscumin from mistletoe. 

Viscum contain lectins that are cytotoxic by inhibiting protein synthesis on the ribosomal level in a manner similar to the toxalbumins ricin and abrin. Viscotoxin and phoratoxin are cardiac toxins and vasoconstrictors. Both produced reflex bradycardia, negative inotropic effects, and, in high doses, vasoconstriction of skin and skeletal muscle vessels in animals. 

A group of plant lectins, such as abrin, ricin, and mod-eccin, are highly toxic to eukaryotic cells. Their mode of action consists of inhibition of protein synthesis by enzymatically inactivating the EF-2 binding region of the 60S ribosomal subunit, whereas the diphtheria toxin inactivates the EF-2 protein itself. Ricin is isolated from castor beans and has a molecular weight of 66,000. Like most plant and bacterial toxic proteins, ricin contains two... 

Flexner, J. (1897) The histological changes produced by ricin and abrin intoxications. J Exp Med, 2, 197-216. Foddy, L. and Hughes, R.C. (1986) Interactions of lectins with normal, swainsonine-treated and ricin-resistant... 

Fodstad, O., Olsnes, S. and Pihl, A. (1976) Toxicity, distribution and elimination of the cancerostatic lectins abrin and ricin after parenteral injection into mice. Br J Cancer, 34, 418 425. 

Olsnes, S., Sandvig, K., Eiklid, K. and Pihl, A. (1978b) Properties and action mechanism of the toxic lectin modeccin interaction with cell fines resistant to modeccin, abrin, and ricin. J Supramol Struct, 9, 15-25. 

Wiley, R.G. and Stirpe, F. (1987) Neuronotoxicity of axonally transported toxic lectins, abrin, modeccin and volkensin in rat peripheral nervous system. Neuropathol Appl Neurobiol, 13, 39-53. 

Olsnes S (1976). Abrin and ricin structure and mechanism of action of two toxic lectins. Bull Inst Pasteur, 74, 85-99. 

A lectin from the African plant, Adenia digi-tata, a succulent. Effects similar to those of ricin and abrin ribosome attack. Seeds commercially available. 

ML-1. Lectin found in mistletoe. Comparable in toxicity with ricin and abrin inhibits protein synthesis as does ricin. 

Lectin from Adenia volkensii the Kilyambiti plant, an African succulent. Comparable to ricin and abrin same mechanism and effects on protein synthesis. 

In the late 1800s, Stillmark4 discovered that the beans of the castor plant contained a toxic protein, which he named ricin. He discovered that ricin caused agglutination of erythrocytes and precipitation of serum proteins. (The lectin properties of ricin and abrin [a closely related toxin from the bean of Abrus precatorius] and their use as tools for research were described in 1972 by Sharon and Lis.5)... 

Sandvig K, Olsnes S, Pihl A. Kinetics of binding of the toxic lectins abrin and ricin to surface receptors of human cells. J Biol Chem. 1976 251 (13) 3977—3984. 

Lectins (from latin legere=to choose). Term for certain proteins or glycoproteins which specifrcally recognize and bind to (poly)saccharides which may even be bound to lipids or carbohydrates. Important examples are abrin, concanavalin A, ricin and phasin. L. are abundant in most organisms, very high contents are found in beans and slugs. The Mr of L. ranges from... 

T. from plants (phytotoxins) include both high- and low-molecular weight substances. Examples of the former are the lectins distributed in legumes (abrin, con-canavalin A, crotin, phasin, ricin). The low-molecular weight plant T. are more numerous and of greater diversity, including the cardiac glycosides, saponins. 

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