Search Organism: All OrganismsArabidopsis thalianaBacillus subtilis 168Bos taurusCaenorhabditis elegansCanis familiarisDanio rerioDrosophila melanogasterEquus caballusEscherichia coli K12Gallus gallusHomo sapiensMacaca mulattaMus musculusNematostella vectensisOryza sativaPan troglodytesRattus norvegicusSaccharomyces cerevisiaeSchizosaccharomyces pombeStrongylocentrotus purpuratusTakifugu rubripesXenopus laevis home help / support contribute downloads mirrors about us J. Biol. Chem. Jan (2002); 277(3):1662-8 Factor XI binding to the platelet glycoprotein Ib-IX-V complex promotes factor XI activation by thrombin. Baglia FA, Badellino KO, Li CQ, Lopez JA, Walsh PN The Sol Sherry Thrombosis Research Center and Department of Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA. Abstract: Factor XI binds to high affinity sites on the surface of stimulated platelets where it is efficiently activated by thrombin. Here, we provide evidence that the factor XI binding site on platelets is in the glycoprotein (GP) Ibalpha subunit of the GP Ib-IX-V complex as follows. 1) Bernard-Soulier platelets, lacking the complex, are deficient in factor XI binding; 2) two GP Ibalpha ligands, SZ-2 (a monoclonal antibody) and bovine von Willebrand factor, inhibit factor XI binding to platelets; 3) by surface plasmon resonance, factor XI bound specifically to glycocalicin (the extracellular domain of GP Ibalpha) in Zn(2+)-dependent fashion (K(d)( app) approximately 52 nm). We then investigated whether glycocalicin could promote factor XI activation by thrombin, another GP Ibalpha ligand. In the presence of high molecular weight kininogen (45 nm), Zn(2+) and Ca(2+) ions, thrombin activated factor XI in the presence of glycocalicin at rates comparable with those seen in the presence of dextran sulfate (1 microg/ml). With higher high molecular weight kininogen concentrations (360 nm), the rate of thrombin-catalyzed factor XI activation in the presence of glycocalicin was comparable with that on activated platelets. Thus, factor XI binds to the GP Ib-IX-V complex, promoting its activation by thrombin. [PUBMED: 11696542] Copyright © 2009, Tyers Lab, The Samuel Lunenfeld Research Institute, Mount Sinai Hospital, All Rights Reserved. terms and conditions - privacy policy - Osprey Network Visualization System BioGRID: A General Repository for Interaction Datasets. Chris Stark, Bobby-Joe Breitkreutz, Teresa Reguly, Lorrie Boucher, Ashton Breitkreutz, Mike Tyers. Nucleic Acids Res. Jan 1;34:D535-9.