Seeing the forest through the trees: characterizing the glycoproteome

Post-translational modifications (PTMs) immensely expand the diversity of the proteome. Glycosylation, among the most ubiquitous PTMs, is a dynamic and multifarious modification of proteins and lipids that generates an omnipresent foliage on the cell surface. The resulting protein glycoconjugates can serve important functions in biology. However, their vast complexity complicates the study of their structures, interactions, and functions. There is now a growing appreciation of the need to study glycans and proteins together as complete entities, as the sum of these two components can exhibit unique functions. In this review, we discuss the growing forestry toolbox to characterize the structure, interactions, and biological functions of protein glycoconjugates, as well as the potential payouts of understanding and controlling these enigmatic biomolecules.