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Updated: Aug 14, 2026

A Uniform Shear Assay for Human Platelet and Cell Surface Receptors via Cone-plate Viscometry
Published on: June 5, 2019
Glycoprotein Ibalpha-bound thrombin functions as a serine protease to produce macromolecular activators of
H Sakamoto1, M Ueno, W Yanghong
12nd Department of Pathology, Kagawa Medical University, Kagawa, 761-0793, Japan.
Abstract:
Production of macromolecular activators of phagocytosis from platelets (MAPPs) was observed when the lysate of fresh platelets was incubated with MAPP precursors and thrombin. An 800-Da MAPP activator (PMA-II) was obtained by Superdex peptide gel filtration of the lysate after thrombin treatment. The necessity of thrombin in MAPP production in fresh platelets was confirmed by the action of anti-thrombin monoclonal antibody or anti-thrombin III and heparin. To specify the thrombin receptor on which the thrombin forming PMA-II binds, the effects of thrombin-receptor-derived peptides and anti-thrombin receptor antibodies on MAPP production by stored platelets which have lost their thrombin content were investigated. DYYPEEDTEGD involved in glycoprotein Ibalpha and anti-glycoprotein Ibalpha antibody prevented stored platelets from producing MAPP. These observations suggest that thrombin bound to glycoprotein Ibalpha functions as a serine protease in MAPP formation.
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