title: Glycoprotein Ibalpha-bound thrombin functions as a serine protease to produce macromolecular activators of phagocytosis from platelets.
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.
authors.affiliation: 2nd Department of Pathology, Kagawa Medical University, Kagawa, 761-0793, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Sakamoto
authors.forename: M
authors.initials: M
authors.lastname: Ueno
authors.forename: W
authors.initials: W
authors.lastname: Yanghong
authors.forename: R
authors.initials: R
authors.lastname: Khatun
authors.forename: S
authors.initials: S
authors.lastname: Tanaka
authors.forename: K
authors.initials: K
authors.lastname: Miyabe
authors.forename: Y
authors.initials: Y
authors.lastname: Ogawa
authors.forename: M
authors.initials: M
authors.lastname: Onodera
mesh_terms: D000595:Amino Acid Sequence; D001792:Blood Platelets / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D010587:Phagocytosis; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism*; D013917:Thrombin / Q000378:metabolism*
chemical_list: D010980:Platelet Membrane Glycoproteins; D013917:Thrombin