Title : Elucidation of N-glycosylation
sites on human platelet
proteins : a glycoproteomic approach
Abstract :
- Among known platelet proteins , a prominent and functionally important group is represented by glycoprotein isoforms
- They account e.g. for secretory proteins and plasma membrane receptors including integrins and glycoprotein VI as well as intracellular components of cytosol and organelles including storage proteins ( multimerin 1 etc.)
- Although many of those proteins have been studied for some time with regard to their function, little attention has been paid with respect to their glycosylation sites
- Here we report the analysis of N-glycosylation sites of human platelet proteins
- For the enrichment of glycopeptides , lectin affinity chromatography as well as chemical trapping of protein bound oligosaccharides was used
- Therefore, concanavalin A was used for specific interaction with carbohydrate species along with periodic acid oxidation and hydrazide bead trapping of glycosylated proteins
- Derivatization by peptide:N-glycosidase F yielded deglycosylated peptides , which provided the basis for the elucidation of proteins and their sites of modification
- Using both methods in combination with nano-LC- ESI-MS/MS analysis 70 different glycosylation sites within 41 different proteins were identified
- Comparison with the Swiss- Prot database established that the majority of these 70 sites have not been specifically determined by previous research projects
- With this approach including hydrazide bead affinity trapping, the immunoglobulin receptor G6f , which is known to couple to the Ras-mitogen-activated protein kinase pathway in the immune system, was shown here for the first time to be present in human platelets