Concepts of glycobiology

This chapter provides an overview of concepts within the field of glycobiology. Because glycan structures are created by glycosyltransferases and are recognized by lectins, glycobiology encompasses the study of these proteins as well as the glycans themselves. There are a large number of possible hexoses and related structures, but only a small fraction of these monosaccharide units are found in glycoconjugates. Similarly, the monosaccharide units could potentially be combined in many different ways through different linkages, but the glycosyltransferases catalyse synthesis of only a limited number of the possible structures. Nevertheless, there is great diversity in the glycan portions of glycoconjugates. It is often difficult to assign functions to specific glycans because the functions may only be evident in an organismal context, and gene knockout approaches may be required to probe these roles.