– The A chain is responsible for inhibiting protein synthesis through the catalytic inactivation of 60S ribosomal subunits by removing adenine from position 4,324 of 28S rRNA. Abrin-a is more toxic than ricin.; The B chain is a galactose-specific lectin that facilitates the binding of abrin to the cell membrane that precedes endocytosis. Abrin-a Protein, Abrus precatorius, Recombinant (E. coli, His) is expressed in E. coli expression system with N-10xHis tag. The predicted molecular weight is 33.6 kDa and the accession number is P11140.