Medical College of Wisconsin
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Comprehensive analysis of platelet glycoprotein Ibα ectodomain glycosylation. J Thromb Haemost 2023 Apr;21(4):995-1009

Date

02/06/2023

Pubmed ID

36740532

Pubmed Central ID

PMC10065957

DOI

10.1016/j.jtha.2023.01.009

Scopus ID

2-s2.0-85150252223 (requires institutional sign-in at Scopus site)   20 Citations

Abstract

BACKGROUND: Platelet glycoprotein (GP) Ibα is the major ligand-binding subunit of the GPIb-IX-V complex that binds von Willebrand factor. GPIbα is heavily glycosylated, and its glycans have been proposed to play key roles in platelet clearance, von Willebrand factor binding, and as target antigens in immune thrombocytopenia syndromes. Despite its importance in platelet biology, the glycosylation profile of GPIbα is not well characterized.

OBJECTIVES: The aim of this study was to comprehensively analyze GPIbα amino acid sites of glycosylation (glycosites) and glycan structures.

METHODS: GPIbα ectodomain that was recombinantly expressed or that was purified from human platelets was analyzed by Western blot, mass spectrometry glycomics, and mass spectrometry glycopeptide analysis to define glycosites and the structures of the attached glycans.

RESULTS: We identified a diverse repertoire of N- and O-glycans, including sialoglycans, Tn antigen, T antigen, and ABO(H) blood group antigens. In the analysis of the recombinant protein, we identified 62 unique O-glycosites. In the analysis of the endogenous protein purified from platelets, we identified 48 unique O-glycosites and 1 N-glycosite. The GPIbα mucin domain is densely O-glycosylated. Glycosites are also located within the macroglycopeptide domain and mechanosensory domain.

CONCLUSIONS: This comprehensive analysis of GPIbα glycosylation lays the foundation for further studies to determine the functional and structural roles of GPIbα glycans.

Author List

Hollenhorst MA, Tiemeyer KH, Mahoney KE, Aoki K, Ishihara M, Lowery SC, Rangel-Angarita V, Bertozzi CR, Malaker SA

Author

Kazuhiro Aoki PhD Associate Professor in the Cell Biology, Neurobiology and Anatomy department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Blood Platelets
Glycosylation
Humans
Platelet Glycoprotein GPIb-IX Complex
Protein Binding
Protein Structure, Tertiary
Recombinant Proteins
von Willebrand Factor