[2][3] X-ray studies have shown that the folding of the polypeptide chains in the region of the carbohydrate-binding sites is also similar, despite differences in the primary sequences.

The carbohydrate-binding sites of these lectins consist of two conserved amino acids on beta pleated sheets.

One of these loops contains transition metals, calcium and manganese, which keep the amino acid residues of the sugar-binding site at the required positions.

[4][5] Some legume lectins are proteolytically processed to produce two chains, beta (which corresponds to the N-terminal) and alpha (C-terminal).

The lectin concanavalin A (conA) from jack bean is exceptional in that the two chains are transposed and ligated (by formation of a new peptide bond).