A toxic lectin and hemagglutinin obtained from seeds of jequirity, Abrus precatorius L., Leguminosae, a common vine of tropical countries, also found in central and southern Florida. Isoln and purification: J. Y. Lin et al., J. Formos. Med. Assoc. 68, 518 (1969), C.A. 72, 98695 (1970); eidem, Toxicon 9, 97 (1971). The high toxicity of abrin was originally believed to result from its hemagglutinating activity, but subsequent studies have shown that separate proteins are responsible for the toxicity and agglutination: S. Olsnes, A. Pihl, Eur. J. Biochem. 35, 179 (1973). Five glycoproteins have been purified from the seeds of A. precatorius: Abrus agglutinin and the toxic principles, abrins a-d. Abrus agglutinin is a tetramer of 134,900 Da, is non-toxic to animal cells and a potent hemagglutinator. Abrins a through d (mol wt 63,000-67,000 Da) are composed of two disulfide-linked polypeptide chains. The smaller A-chain inhibits protein synthesis and causes cell death; the larger B-chain binds to the cell plasma membrane. Purification of major components: C. H. Wei et al., J. Biol. Chem. 249, 3061 (1974). Crystallographic study: C. H. Wei, J. R. Einstein, ibid. 2985. Improved purification, properties, crystallography of Abrus agglutinin: C. H. Wei et al., ibid. 250, 4790 (1975). Physical properties of the toxic principles: M. S. Herrmann, W. D. Behnke, Biochim. Biophys. Acta 621, 43 (1980); eidem, ibid. 667, 397 (1981). Isoln and purification of all five proteins: J. Y. Lin et al., Toxicon 19, 41 (1981). Amino acid sequence of the A-chain of abrin-a and comparison with ricin: G. Funatsu et al., Agric. Biol. Chem. 52, 1095 (1988). Antitumor effects in animals: V. V. S. Reddy, M. Sirsi, Cancer Res. 29, 1447 (1969); J. Y. Lin et al., Nature 227, 292 (1970); O. Fodstad et al., Cancer Res. 37, 4559 (1977). Immunoelectron microscopy studies of abrin toxic action on tumor cells: C. T. Lin et al., J. Ultrastruct. Res. 73, 310 (1980). Studies on toxicity and binding kinetics: M. Witten et al., Exp. Cell Biol. 49, 306 (1981); C. E. Bennett et al., ibid. 319. Use of A-chain in cell-type-specific cytotoxic agents known as “immunotoxins”: A. J. Cumber et al., Methods Enzymol. 112, 207 (1985). Toxicity study: J. Y. Lin et al., J. Formos. Med. Assoc. 68, 322 (1969), C.A. 71, 121926 (1969). See also Ricin, Lectins.