Ricin binding site

A ricin-resistant mouse lymphoma cell line has been isolated which was shown to possess a normal number of ricin-binding sites [63-66]. These cells internalized reduced amounts of ferritin-ricin complexes at low toxin concentrations compared with the parent cells. Resistance in this cell line is therefore due to a defect in transferring ricin from the cell surface to the cytoplasm, since... 

Reported applications of DSS include crosslinking the A and B subunits of ricin (Montesano et al., 1982), studying human somatotropin and the components of the lactogenic-binding sites of rat liver (Caamano et al., 1983), crosslinking CSF-1 to its cell-surface receptor (Morgan... 

The ricin and abnn A chains used to block high affinity binding sites on the column should be alkylated to remove the free sulfhydryl group that could interfere with conjugate purification... 

Specific metal ion binding sites are directly observed in the crystal structures of hammerhead ribozymes [18], P4—P6 domain of Tetrahymena group I intron [19], transfer (tRNA) [20], GAAA tetraloop receptor [21], sarcin-ricin loop [22], and MMTV pseudoknots [23], for example. High... 

CBM Family 13 adopt the p-trefoil fold first encountered with the ricin B (carbohydrate-binding) chain. It contains 12 strands of p-sheet arranged in such a way as to provide three independent sugar binding sites with different specificities, and again binding is enthalpy driven. 

Like ricin, abrin is a type 2 ribosome inactivating protein with A and B chains linked by a disulphide bond. The abrin A chain comprises 251 amino acid residues compared to 267 in the ricin A chain, both having three folding structural domains and a molecular weight of approximately 30 kDa. The abrin B chain has a molecular weight of 35 kDa with 60% of its amino acid residues identical to those of ricin s B chain. Both B chains have two saccharide binding sites which are highly conserved between the two toxins. 

Abrin- and ricin-resistant variants of established HeLa cell lines have been characterized. The reduced number of binding sites on two of the cell variants is due to an increased level of neuraminic acid on oligosaccharide chains terminated at the non-reducing end by D-galactose. However, these over-sialylated variants are not cross-resistant to another plant toxin, modeccin,... 

The roots of Adenia digitata contain the toxic lectin modeccin, which, like abrin and ricin, consists of two dissimilar peptide chains and acts by inactivating ribosomes. - Terminal D-galactosyl residues on receptor molecules are involved in the binding sites of all three molecules. 

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