Pokeweed antiviral proteins enzymatically inactivate the 60 S subunit of eucaryotic ribosomes in cell-free preparations. Three different species of the enzyme can be isolated from spring leaves, summer leaves, and seeds of pokeweed. Sequence analyses of the NH2-terminal residues show that pokeweed antiviral protein, isolated from spring leaves and seeds, are homologous and differ in 11 of the 2...

The molecular action of ricin A chain involves cleavage of the N-glycosidic bond between ribose and the adenine 4324 nucleotides from the 5' end of mammalian 28 S rRNA (Endo, Y., and Tsurugi, K. (1987) J. Biol. Chem. 262, 8128-8130). In this paper, four ricin- and abrin-resistant Chinese hamster ovary cell mutants that possess ribosomes resistant to this N-glycosidase action are described. Thre...

Highly specific antibodies (affinity-purified or hybridoma) directed against cell surface immunoglobulins on normal or neoplastic murine B lymphocytes were covalently coupled to the A chain of the plant toxin ricin. Such conjugates containing antibodies specific for IgM, for either of the two allotypes of IgD, or for the idiotype of the B cell tumor BCL1 rapidly bound in vitro to cells expressi...

A cell-free translation assay was applied for the quick detection of ricin in food samples. Three economically important foods-ground beef, low-fat milk, and liquid chicken egg--were tested. The results indicated that ground beef had very little matrix effect on the assay, whereas low-fat milk and liquid chicken egg showed clear interference on the protein translation. A simple dilution in phos...

Ricin is a potent toxin and a potential bioterrorism weapon with no specific countermeasures or vaccines available. The holotoxin is composed of two polypeptide chains linked by a single disulfide bond: the A-chain (RTA), which is an N-glycosidase enzyme, and the B-chain (RTB), a lectin polypeptide that binds galactosyl moieties on the surface of the mammalian target cells. Previously (McHugh e...

A number of compounds that interfere with glycoprotein synthesis and transport have been tested for their ability to sensitize cells to cancerostatic protein toxins. Tunicamycin, swainsonine, cycloheximide, and puromycin sensitized Vero cells and HeLa cells to abrin and ricin, as we have found previously with monensin (K. Sandvig and S. Olsnes, J. Biol. Chem., 257: 7504-7513, 1982). Cycloheximi...

This paper describes a protocol for the preparation of highly purified A (A1 and A2) and B chains of the plant toxin, ricin, and biochemical and biological characterization of these proteins. Intact ricin was bound to acid-treated Sepharose 4B and was split on the column into A and B chains with 2-mercaptoethanol. The A chains were eluted with borate buffer containing 2-mercaptoethanol. A1 and ...

PB10 is a murine monoclonal antibody against an immunodominant epitope on ricin toxin's enzymatic subunit. Here, we characterize a fully humanized version of PB10 IgG1 (hPB10) and demonstrate that it has potent in vitro and in vivo toxin-neutralizing activities. We also report the minimum serum concentrations of hPB10 required to protect mice against 10 times the 50% lethal dose of ricin when d...