Lectin .................................................................................................. 21 1.6 Concluding Remarks ......................................................................................22 Acknowledgments ....................................................................................................23 References ................................................................................................................23

Carbohydrate-binding proteins and glycoproteins are the focus of intense scientiˆc investigation due to their central role in diverse biological processes that include, but are not limited to, immunity and infection, cellular adhesion, and cellular communication and signaling. Yet, our understanding of the fundamental molecular mechanisms through which carbohydrate-binding proteins and glycoproteins realize their functions still remains underdeveloped. Of note, while it is estimated that over 50% of all eukaryotic proteins are glycosylated (Apweiler et al. 1999), only around 5% of the three-dimensional (3D) structures deposited in structural databases such as the Protein Data Bank (PDB) (Berman et al. 2000) include proteins with N-or O-linked carbohydrates (often called glycans). Similarly, only around 7% of all PDB entries contain information on protein/carbohydrate systems (covalently or noncovalently bound to proteins), and there are even fewer examples of highresolution structures where the associated carbohydrate components have been fully resolved (Lutteke 2009).