title: The cDNA cloning and molecular characterization of a snake venom platelet glycoprotein Ib-binding protein, mamushigin, from Agkistrodon halys blomhoffii venom.
abstract: The entire cDNA sequences of a novel snake venom platelet glycoprotein (GP) Ib-binding protein (BP) composed of an alpha/beta heterodimeric structure, termed mamushigin, from Agkistrodon halys blomhoffii were determined, that include the leader peptides (21/23 amino acid residues) and mature subunits (136/123 amino acid residues). The mature subunits of mamushigin are 37.5% identical, and showed a high degree of similarity (37.7-67.5% identity) with the respective subunits of group VII C-type lectins (19). The sequences of the leader peptides of the mamusigin subunits showed the highest similarity (alpha-73.9/beta-82.6%) with those of factor IX/X-BP from Trimeresurus flavoviridis, and the cleavage site residue in both proteins was the same Ala(-1). The GPIb-binding specificity of mamushigin is strongly supported by several lines of evidence, but mamushigin can directly aggregate normal platelets, similar to alboaggregin-B (AL-B) (1). This differs from other GPIb-BP's. In mamushigin-treated platelets, serotonin was not released, and flow cytometric analysis using a monoclonal antibody PAC-1 totally excluded platelet GPIIb/IIIa activation. Mamushigin enhanced platelet aggregation at low-shear stress, and this effect totally disappeared in the presence of GPIb-receptor blockers specific for von Willebrand factor binding, but not by GPIIb/IIIa-receptor blockers. At high-shear stress, mamushigin blocked platelet aggregation in a dose-dependent manner, as seen with other GPIb-BP's. This paper, therefore, describes the cDNA cloning and molecular characterization of mamushigin which has a different effect on platelet aggregation under different shear stress.
authors.affiliation: Department of Pediatrics and Blood Transfusion Medicine, Nara Medical University, Kashihara, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Sakurai
authors.forename: Y
authors.initials: Y
authors.lastname: Fujimura
authors.forename: T
authors.initials: T
authors.lastname: Kokubo
authors.forename: K
authors.initials: K
authors.lastname: Imamura
authors.forename: T
authors.initials: T
authors.lastname: Kawasaki
authors.forename: M
authors.initials: M
authors.lastname: Handa
authors.forename: M
authors.initials: M
authors.lastname: Suzuki
authors.forename: T
authors.initials: T
authors.lastname: Matsui
authors.forename: K
authors.initials: K
authors.lastname: Titani
authors.forename: A
authors.initials: A
authors.lastname: Yoshioka
mesh_terms: D017836:Agkistrodon / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D003001:Cloning, Molecular; D003435:Crotalid Venoms / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D019281:Dimerization; D008969:Molecular Sequence Data; D010974:Platelet Aggregation / Q000187:drug effects; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D011498:Protein Precursors / Q000235:genetics; D021382:Protein Sorting Signals / Q000737:chemistry / Q000235:genetics; D012310:Ristocetin / Q000037:antagonists & inhibitors; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013314:Stress, Mechanical; D013329:Structure-Activity Relationship; D013915:Thrombasthenia / Q000097:blood
chemical_list: D002352:Carrier Proteins; D003435:Crotalid Venoms; D018076:DNA, Complementary; D019038:Platelet Glycoprotein GPIb-IX Complex; D011498:Protein Precursors; D021382:Protein Sorting Signals; C114784:mamushigin; D012310:Ristocetin; C030961:botrocetin