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Blood, 1 October 2008, Vol. 112, No. 7, pp. 2795-2802. Prepublished online as a Blood First Edition Paper on June 27, 2008; DOI 10.1182/blood-2008-02-138941. This Article Full Text Full Text (PDF) All Versions of this Article: blood-2008-02-138941v1 112/7/2795    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 Majumder, R. Articles by Lentz, B. R. Search for Related Content PubMed PubMed Citation Articles by Majumder, R. Articles by Lentz, B. R. Related Collections Hemostasis, Thrombosis, and Vascular Biology Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  HEMOSTASIS, THROMBOSIS, AND VASCULAR BIOLOGY A phosphatidylserine binding site in factor Va C1 domain regulates both assembly and activity of the prothrombinase complex Rinku Majumder1, Mary Ann Quinn-Allen2, William H. Kane2, and Barry R. Lentz1 1 Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill; and 2 Division of Hematology, Departments of Medicine and Pathology, Duke University Medical Center, Durham, NC Tightly associated factor Va (FVa) and factor Xa (FXa) serve as the essential prothrombin-activating complex that assembles on phosphatidylserine (PS)–containing platelet membranes during blood coagulation. We have previously shown that (1) a soluble form of PS (C6PS) triggers assembly of a fully active FVa-FXa complex in solution and (2) that 2 molecules of C6PS bind to FVa light chain with one occupying a site in the C2 domain. We expressed human factor Va (rFVa) with mutations in either the C1 domain (Y1956,L1957)A, the C2 domain (W2063,W2064)A, or both C domains (Y1956,L1957,W2063,W2064)A. Mutations in the C1 and C1-C2 domains of rFVa reduced the rate of activation of prothrombin to thrombin by FXa in the presence of 400 µM C6PS by 14 000- to 15 000-fold relative to either wild-type or C2 mutant factor rFVa. The Kd's of FXa binding with rFVa (wild-type, C2 mutant, C1 mutant, and C1-C2 mutant) were 3, 4, 564, and 624 nM, respectively. Equilibrium dialysis experiments detected binding of 4, 3, and 2 molecules of C6PS to wild-type rFVa, C1-mutated, and C1,C2-mutated rFVa, respectively. Because FVa heavy chain binds 2 molecules of C6PS, we conclude that both C2 and C1 domains bind one C6PS, with binding to the C1 domain regulating prothrombinase complex assembly. CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? This article has been cited by other articles: M. H. A. Bos, M. Boltz, L. St. Pierre, P. P. Masci, J. de Jersey, M. F. Lavin, and R. M. Camire Venom factor V from the common brown snake escapes hemostatic regulation through procoagulant adaptations Blood, July 16, 2009; 114(3): 686 - 692. [Abstract] [Full Text] [PDF] C. Oslakovic, M. J. Krisinger, A. Andersson, M. Jauhiainen, C. Ehnholm, and B. Dahlback Anionic Phospholipids Lose Their Procoagulant Properties When Incorporated into High Density Lipoproteins J. Biol. Chem., February 27, 2009; 284(9): 5896 - 5904. [Abstract] [Full Text] [PDF]

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