Folding of glycoproteins: toward understanding the biophysics of the glycosylation code

Glycosylation is among the most common post-translational modifications that proteins undergo that may affect many of their activities. It may also modify the underlying energy landscape of glycoproteins in a way that their altered biophysical characteristics are linked to their bioactivity. Yet, the capability of glycosylation to modify thermodynamic and kinetic properties varies greatly between glycoproteins. Deciphering the 'glycosylation code' that dictates the interplay between the nature of the carbohydrates or the proteins and the biophysical properties of the glycosylated proteins is essential. In this article, we discuss how the size, number, and structure of glycans, as well as the attachment sites, may modulate the folding of glycoproteins. Understanding the cross-talks between the protein and the attached glycans at the molecular level may assist in tailoring the biophysical properties of proteins in general.