24 February 2017
The hemostatic system comprises platelet aggregation, coagulation, and fibrinolysis, and is critical to the maintenance of vascular integrity. Here we performed the first systematic analysis of native-O-glycosylation using lectin affinity chromatography coupled to liquid chromatography mass spectrometry (LC-MS)/MS to determine the precise location of O-glycans in human plasma, platelets, and endothelial cells, which coordinately regulate hemostasis. We identified the hitherto largest O-glycoproteome from native tissue with a total of 649 glycoproteins and 1123 nonambiguous O-glycosites, demonstrating that O-glycosylation is a ubiquitous modification of extracellular proteins. Using an unbiased screen to identify associations between O-glycosites and protein annotations we found that O-glycans were over-represented close (± 15 amino acids) to tandem repeat regions, protease cleavage sites, within propeptides, and located on a select group of protein domains. The importance of O-glycosites in proximity to proteolytic cleavage sites was further supported by in vitro peptide assays demonstrating that proteolysis of key hemostatic proteins can be inhibited by the presence of O-glycans. Collectively, these data illustrate the global properties of native O-glycosylation and provide the requisite roadmap for future biomarker and structure-function studies.
King SL, Joshi HJ, Schjoldager KT, Halim A, Madsen TD, Dziegiel MH, Woetmann A, Vakhrushev SY and Wandall HH (2017): Characterizing the O-glycosylation landscape of human plasma, platelets, and endothelial cells. Blood Advances 1:429-442.