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Blood, 1 March 2005, Vol. 105, No. 5, pp. 1986-1991. Prepublished online as a Blood First Edition Paper on October 28, 2004; DOI 10.1182/blood-2004-04-1365. This Article Full Text Full Text (PDF) All Versions of this Article: 2004-04-1365v1 105/5/1986    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Cruz, M. A. Articles by López, J. A. Search for Related Content PubMed PubMed Citation Articles by Cruz, M. A. Articles by López, J. A. Related Collections Cell Adhesion and Motility Signal Transduction Hemostasis, Thrombosis, and Vascular Biology Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  HEMOSTASIS, THROMBOSIS, AND VASCULAR BIOLOGY The platelet glycoprotein Ib–von Willebrand factor interaction activates the collagen receptor 21 to bind collagen: activation-dependent conformational change of the 2-I domain Miguel A. Cruz, Junmei Chen, Jody L. Whitelock, Liza D. Morales, and José A. López From the Thrombosis Research Section, Department of Medicine, Baylor College of Medicine, Houston, TX. Integrin 21 (glycoprotein [GP] Ia/IIa) is a major platelet receptor for collagen, containing its collagen-binding site within the 2 I domain. 21 changes conformation upon platelet activation, increasing its affinity for collagen. We observed that 2 antibodies known to bind within the 2I domain, 12F1 and 6F1, bound preferentially to adenosine diphosphate (ADP)–activated platelets. Interestingly, when whole blood was perfused over a surface coated with either 12F1 or 6F1, only 6F1 supported the adhesion of unstimulated platelets. To test whether the interaction of GP Ib with von Willebrand factor (VWF) directly activates 21, we used 12F1 as a probe of integrin activation. We perfused blood over a surface coated with a mixture of VWF-A1 domain (a GP Ib ligand) and 12F1 or VWF-A1 and mouse immunoglobulin G (IgG). Platelets rolled and did not attach stably on the A1/IgG surface, but they firmly bound and covered the A1/12F1 surface. We corroborated that 12F1 binds an active conformation of the I domain by showing that it binds with higher affinity to a gain-of-function mutant than to either wild-type I domain or a loss-of-function mutant. These results strongly suggest that the interaction of platelet GP Ib with VWF mediates the activation of 21, increasing its affinity for collagen. CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? This article has been cited by other articles: L. J. Lambert, A. A. Bobkov, J. W. Smith, and F. M. Marassi Competitive Interactions of Collagen and a Jararhagin-derived Disintegrin Peptide with the Integrin {alpha}2-I Domain J. Biol. Chem., June 13, 2008; 283(24): 16665 - 16672. [Abstract] [Full Text] [PDF] C. N. Morrell, K. Murata, A. M. Swaim, E. Mason, T. V. Martin, L. E. Thompson, M. Ballard, K. Fox-Talbot, B. Wasowska, and W. M. Baldwin III In Vivo Platelet-Endothelial Cell Interactions in Response to Major Histocompatibility Complex Alloantibody Circ. Res., April 11, 2008; 102(7): 777 - 785. [Abstract] [Full Text] [PDF] A. Kauskot, F. Adam, A. Mazharian, N. Ajzenberg, E. Berrou, A. Bonnefoy, J.-P. Rosa, M. F. Hoylaerts, and M. Bryckaert Involvement of the Mitogen-activated Protein Kinase c-Jun NH2-terminal Kinase 1 in Thrombus Formation J. Biol. Chem., November 2, 2007; 282(44): 31990 - 31999. [Abstract] [Full Text] [PDF] E. Calvo, F. Tokumasu, O. Marinotti, J.-L. Villeval, J. M. C. Ribeiro, and I. M. B. Francischetti Aegyptin, a Novel Mosquito Salivary Gland Protein, Specifically Binds to Collagen and Prevents Its Interaction with Platelet Glycoprotein VI, Integrin {alpha}2beta1, and von Willebrand Factor J. Biol. Chem., September 14, 2007; 282(37): 26928 - 26938. [Abstract] [Full Text] [PDF] W. L. Connors, J. Jokinen, D. J. White, J. S. Puranen, P. Kankaanpaa, P. Upla, M. Tulla, M. S. Johnson, and J. Heino Two Synergistic Activation Mechanisms of {alpha}2beta1 Integrin-mediated Collagen Binding J. Biol. Chem., May 11, 2007; 282(19): 14675 - 14683. [Abstract] [Full Text] [PDF] C. Sucker, B. Senft, R. E. Scharf, and R. B. Zotz Determination of von Willebrand Factor Activity: Evaluation of the HaemosILTM Assay in Comparison With Established Procedures. Clinical and Applied Thrombosis/Hemostasis, July 1, 2006; 12(3): 305 - 310. [Abstract] [PDF] S. Massberg, I. Konrad, K. Schurzinger, M. Lorenz, S. Schneider, D. Zohlnhoefer, K. Hoppe, M. Schiemann, E. Kennerknecht, S. Sauer, et al. Platelets secrete stromal cell-derived factor 1{alpha} and recruit bone marrow-derived progenitor cells to arterial thrombi in vivo J. Exp. Med., May 15, 2006; 203(5): 1221 - 1233. [Abstract] [Full Text] [PDF] I. del Conde, M. A. Cruz, H. Zhang, J. A. Lopez, and V. Afshar-Kharghan Platelet activation leads to activation and propagation of the complement system J. Exp. Med., March 21, 2005; 201(6): 871 - 879. [Abstract] [Full Text] [PDF]

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