ABSTRACT

Approximately 50% of all human proteins are glycosylated (Apweiler et al. 1999). Because glycosylation takes place in the secretory pathway of the cell, the vast majority (>90%) of proteins on the cell surface and secreted in body fluids is modified by glycosylation. Aberrant glycosylation of plasma proteins has been reported in many human diseases ranging from monogenetic inherited disorders to common diseases such as cancer (Walt et al. 2012). The majority of tumor biomarkers that are currently approved by the FDA are glycoproteins (Fuzery et al. 2013). However, the glycan part of these markers has hitherto been largely neglected.