Fig. S6.

CBS versatility resulting from the stereochemistry of protein–carbohydrate interactions. (A) Close-ups of the CBSs of legume lectins complexed with their receptors. Note that, in each case, monosaccharide binding relies on a strictly conserved 3-aa assembly, but that unique specificity is attained by binding of the dedicated ligands (galactose or mannose and glucose) in different orientations (through hydrogen bonding with 3- and 4-OH or 4- and 6-OH, respectively) (45–48). (B) Close-ups of the CBSs of mammalian C-type lectins mannose-binding proteins A and C. Note the similarity between binding sites with hydrogen-bonding and Ca²⁺ coordination of the vicinal, equatorial 3- and 4-OH groups, and the difference in mannose binding topologies, with the sugar’s pyranose ring rotated 180° (44).