Vertebrate protein glycosylation: diversity, synthesis and function

Approximately half of human proteins are glycosylated, and the resulting diverse glycan patterns encode an additional level of information. The process of protein glycosylation is mediated by numerous enzymes with dynamic localization, regulation and specificity. High-throughput techniques facilitate the study of complex protein glycans and may give further insights into their roles in protein homeostasis, cell signalling and cell adhesion. Protein glycosylation is a ubiquitous post-translational modification found in all domains of life. Despite their significant complexity in animal systems, glycan structures have crucial biological and physiological roles, from contributions in protein folding and quality control to involvement in a large number of biological recognition events. As a result, they impart an additional level of 'information content' to underlying polypeptide structures. Improvements in analytical methodologies for dissecting glycan structural diversity, along with recent developments in biochemical and genetic approaches for studying glycan biosynthesis and catabolism, have provided a greater understanding of the biological contributions of these complex structures in vertebrates.