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Coagulation factor Va is an actin filament binding and cross-linking protein
E Furmaniak-Kazmierczak1, M E Nesheim, G P Côté
1Department of Biochemistry, Queen's University, Kingston, ON, Canada.
Biochemistry and Cell Biology = Biochimie Et Biologie Cellulaire
|January 1, 1995
Summary
Bovine factor Va (activated coagulation factor V) binds to and cross-links actin filaments, a finding potentially relevant to circulation when cells are damaged. This interaction is mediated by the light chain of factor Va.
Area of Science:
- Biochemistry
- Molecular Biology
- Hematology
Background:
- Bovine coagulation cofactor factor Va plays a critical role in the blood coagulation cascade.
- Actin filaments are the main structural component of muscle cells and are involved in various cellular processes.
Purpose of the Study:
- To investigate the interaction between bovine factor Va and skeletal muscle actin filaments.
- To determine the functional and structural characteristics of this interaction and its potential physiological relevance.
Main Methods:
- Biochemical assays to measure binding affinity (dissociation constant) and stoichiometry.
- Viscosity and sedimentation studies to assess the cross-linking activity of factor Va on actin filaments.
- Investigation of the role of the factor Va light chain in actin binding.
Main Results:
- Factor Va binds to F-actin with a dissociation constant of 40-50 nM at 50 mM NaCl, with one factor Va molecule binding per two actin molecules at saturation.
- Factor Va significantly increases actin filament sedimentation and viscosity, indicating cross-linking activity.
- The isolated 74-kDa light chain of factor Va exhibits identical actin binding and cross-linking properties to intact factor Va, suggesting it mediates the interaction.
- Proteolytic activation of factor V is necessary for potent F-actin binding, as factor V binds weakly.
Conclusions:
- Factor Va directly interacts with and cross-links actin filaments via its light chain.
- This interaction is sensitive to ionic strength and requires proteolytic activation.
- The findings suggest a potential physiological role for factor Va-actin interaction in conditions where cellular damage releases actin into circulation.