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Updated: Jun 6, 2026

Comprehensive Analysis of Procoagulant Platelets Exhibiting Features of Necrosis, Apoptosis and Platelet Activation
Published on: May 23, 2025
Prothrombin activation on the activated platelet surface optimizes expression of procoagulant activity
Jeremy P Wood1, Jay R Silveira, Nicole M Maille
1Department of Biochemistry, University of Vermont College of Medicine, 89 Beaumont Avenue, Burlington, VT 05405, USA.
Activated platelets form alpha-thrombin through a specific pathway, initially cleaving prothrombin at Arg271 to generate prethrombin-2, which optimizes clotting and limits anticoagulant effects.
Area of Science:
- Biochemistry
- Hematology
- Molecular Biology
Background:
- Hemostasis requires alpha-thrombin generation by the prothrombinase complex on activated platelets.
- Prothrombinase cleaves prothrombin at Arg271 and Arg320, forming prethrombin-2 or meizothrombin intermediates, respectively.
Purpose of the Study:
- To determine the initial prothrombin cleavage site on activated platelets.
- To investigate the pathway of alpha-thrombin formation on activated platelets.
Main Methods:
- Monitoring prothrombin and mutant cleavage on thrombin- or collagen-activated platelets.
- Utilizing prothrombin mutants lacking Arg271 or Arg320 cleavage sites.
Main Results:
- Prothrombin is initially cleaved at Arg271 to form prethrombin-2, followed by Arg320 cleavage to yield alpha-thrombin.
- This cleavage pathway is independent of factor Va source and platelet releasate components.
- Arg271 effectively competes with Arg320 for initial cleavage, with over 90-95% occurring at Arg271.
Conclusions:
- Activated platelets preferentially utilize the prethrombin-2 pathway for alpha-thrombin generation.
- This pathway optimizes procoagulant activity by limiting meizothrombin's anticoagulant functions.
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