Eukaryotic glycosylation: whim of nature or multipurpose tool?

Protein and lipid glycosylation is a ubiquitous phenomenon. The task of cat aloguing the great structural variety of the glycan part has demanded consi derable efforts over decades. This patient endeavor Has imperative to disce rn the inherent rules of glycosylation which cannot affirm assumptions on a purely coincidental nature of this type of protein and lipid modification. These results together with theoretical considerations uncover a salient p roperty of oligosaccharides. In comparison with amino acids and nucleotides , monosaccharides excel in their potential to serve as units of hardware fo r storing biological information. Thus, the view that glycan chains exclusi vely affect physicochemical properties of the conjugates is indubitably fla wed. This original concept has been decisively jolted by the discovery of e ndogenous receptors (lectins) for distinct glycan epitopes which are as cha racteristic as a fingerprint or a signature for a certain protein (class) o r cell type. Recent evidence documents that these binding proteins are even endowed with the capacity to select distinct low-energy conformers of the often rather flexible oligosaccharides, granting entry to a new level of re gulation of ligand affinity by shifting conformer equilibria. The assessmen t of the details of this recognition by)X-ray crystallography, nuclear magn etic resonance spectroscopy, microcalorimetry and custom-made derivatives i s supposed to justify a guarded optimism in satisfying the need for innovat ive drug design in antiadhesion therapy, for example against viral or bacte rial infections and unwanted inflammation. This review presents a survey of the structural aspects of glycosylation and of evidence to poignantly endo rse the notion that carrier-attached glycan chains can partake in biologica l information transfer at the level of cell compartments, cells and organs.