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The assembly of the factor X-activating complex on activated human platelets
S S Ahmad1, F S London, P N Walsh
1The Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA.
Journal of Thrombosis and Haemostasis : JTH
|July 23, 2003
Summary
Platelets provide crucial surfaces for blood clot formation by binding specific coagulation factors. This interaction is vital for normal hemostasis and has implications for various diseases.
Area of Science:
- Hematology
- Biochemistry
- Cell Biology
Background:
- Platelet membranes are essential for hemostasis, facilitating the assembly of key enzyme complexes.
- Platelets possess specific, high-affinity receptors for numerous coagulation factors and proteases.
Purpose of the Study:
- To review the role of platelet receptors in coagulation factor assembly and activation.
- To explore the hypothesis that specific protein receptors define the procoagulant surface of platelets.
Main Methods:
- Review of recent laboratory studies and published literature.
- Analysis of the molecular interactions between platelets and coagulation factors (XI, IX, X, VIII, V, prothrombin, thrombin).
Main Results:
- Platelet surfaces assemble the factor X-activating complex, comprising receptors for factor IXa, factor X, and factor VIIIa.
- This colocalization accelerates factor X activation by 24 million-fold, crucial for normal hemostasis.
- Evidence suggests specific protein receptors, not just phospholipids, may define the platelet's procoagulant activity.
Conclusions:
- Platelet-coagulation protein interactions are critical for maintaining hemostasis.
- Understanding these interactions is vital for comprehending the pathogenesis of human diseases involving coagulation abnormalities.