Exosomes consist of vesicles that are secreted by several human cells, including
tumor cells and neurons, and they are found in several
biological fluids. Exosomes have characteristic
protein and
lipid composition, however, the results concerning
glycoprotein composition and glycosylation are scarce. Here, protein glycosylation of exosomes from ovarian
carcinoma SKOV3 cells has been studied by
lectin blotting, NP-HPLC analysis of
2-aminobenzamide labeled
glycans and mass spectrometry. An abundant
sialoglycoprotein was found enriched in exosomes and it was identified by
peptide mass fingerprinting and immunoblot as the galectin-3-binding
protein (LGALS3BP). Exosomes were found to contain predominantly complex
glycans of the di-, tri-, and tetraantennary type with or without proximal
fucose and also high
mannose glycans. Diantennary
glycans containing bisecting
N-acetylglucosamine were also detected. This work provides detailed information about
glycoprotein and N-
glycan composition of exosomes from
ovarian cancer cells, furthermore it opens novel perspectives to further explore the functional role of
glycans in the biology of exosomes.