Title: The role of thrombin exosites I and II in the activation of human coagulation factor V
Authors: Segers, Kenneth
Dahlbäck, Björn
Bock, Paul E
Tans, Guido
Rosing, Jan
Nicolaes, Gerry A F # ×
Issue Date: Nov-2007
Publisher: American Society for Biochemistry and Molecular Biology
Series Title: Journal of Biological Chemistry vol:282 issue:47 pages:33915-33924
Abstract: Human blood coagulation Factor V (FV) is a plasma protein with little procoagulant activity. Limited proteolysis at Arg(709), Arg(1018), and Arg(1545) by thrombin or Factor Xa (FXa) results in the generation of activated FV, which serves as a cofactor of FXa in prothrombin activation. Both thrombin exosites I and II have been reported to be involved in FV activation, but the relative importance of these regions in the individual cleavages remains unclear. To investigate the role of each exosite in FV activation, we have used recombinant FV molecules with only one of the three activation cleavage sites available, in combination with exosite I- or II-specific aptamers. In addition, structural requirements for exosite interactions located in the B-domain of FV were probed using FV B-domain deletion mutants and comparison with FV activating enzymes from the venom of Russell's viper (RVV-V) and of Levant's viper (LVV-V) known to activate FV by specific cleavage at Arg(1545). Our results indicate that thrombin exosite II is not involved in cleavage at Arg(709) and that both thrombin exosites are important for recognition and cleavage at Arg(1545). Efficient thrombin-catalyzed FV activation requires both the N- and C-terminal regions of the B-domain, whereas only the latter is required by RVV-V and LVV-V. This indicates that proteolysis of FV by thrombin at Arg(709), Arg(1018), and Arg(1545) show different cleavage requirements with respect to interactions mediated by thrombin exosites and areas that surround the respective cleavage sites. In addition, interactions between exosite I of thrombin and FV are primarily responsible for the different cleavage site specificity as compared with activation by RVV-V or LVV-V.
ISSN: 0021-9258
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Laboratory of Molecular Bacteriology (Rega Institute)
Laboratory for the Research of Neurodegenerative Diseases
× corresponding author
# (joint) last author

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