In this study, we resolved the crystal structures of IPO-Me-Man, IPO-Me-Glc and IPO-Me-Gal complexes. These monosaccharides showed similar orientation to bind to IPO. The binding pocket of IPO contains 6 residues such as Gly21, Tyr97, Gly141, Trp142, Tyr143 and Asp145, to form hydrogen bonds with different monosaccharides (Figure 3 Table 2 ). The carbohydrate binding manner of IPO is not confined as is the mannose-glucose-specific binding lectin.