Protein glycosylation is an important form of posttranslational modiˆcation that plays vital roles in various cellular events. The attachment of carbohydrates on secreted and membrane-bound proteins is necessary for proper protein folding and assembly. Glycosylation can also improve protein stability and modulate protein functions. Speciˆc recognition of glycans on cell surface proteins is an efˆcient way of mediating cell-cell interactions in multicellular organisms, as well as interactions between different organisms.