Thomas Daugbjerg Madsen
O-glycans in Protein and Peptide Stability and Function
Traditionally, O-glycans have been found and associated with large mucins containing P/T/S rich domains with high density of O-glycans, where they serve important functions for the structure and stability of mucins required for lubrication and protective effects on lining mucosa and in body fluids. However, recent proteome-wide discovery strategies for O-glycosylation demonstrate that O-glycans are abundantly found on all types of proteins (>80% of all proteins trafficking the secretory pathway are O-glycosylated, Steentoft et al., 2013), and in particular found in more isolated sites often in close proximity to other important PTMs such as PC processing sites, phosphorylation sites (not published), mannosylation sites, ectodomain shedding sites, and most recently activation of G-coupled protein receptors (GPCRs), where they may serve important (co-)regulatory roles in fine-tuning protein functions (Schjoldager et al.,2010, 2011, 2012, Goth et al., 2015, 2012). Our breakthrough in O-glycoproteomics has opened for wide discovery of O-glycoproteins and is now driving a plethora of exciting novel hypotheses of the role of O-glycosylation for diverse types of protein including GPCRs and LDLR related proteins.