Related Experiment Video
Updated: Jun 20, 2026
08:30
Investigating von Willebrand Factor Pathophysiology Using a Flow Chamber Model of von Willebrand Factor-platelet String Formation
Published on: August 14, 2017
Multi-step binding of ADAMTS-13 to von Willebrand factor
H B Feys1, P J Anderson, K Vanhoorelbeke
1Department of Biochemistry and Molecular Biophysics, Department of Medicine, Washington University, School of Medicine, St Louis, MO, USA.
Journal of Thrombosis and Haemostasis : JTH
|September 22, 2009
Summary
ADAMTS-13 binds to von Willebrand factor (VWF) in circulation. This interaction allows ADAMTS-13 to cleave VWF when it unfolds under shear stress, a key process in thrombus formation.
Area of Science:
- Hematology
- Biochemistry
- Molecular Biology
Background:
- ADAMTS-13 enzyme activity depends on von Willebrand factor (VWF) conformation.
- VWF secondary structure changes are crucial for efficient ADAMTS-13 cleavage.
- ADAMTS-13 recognizes VWF through non-catalytic domains distant from its active site.
Purpose of the Study:
- To investigate the binding of native VWF to ADAMTS-13.
- To test the hypothesis that not all VWF binding sites for ADAMTS-13 are cryptic.
Main Methods:
- Co-immunoprecipitation of VWF-ADAMTS-13 complexes using anti-VWF antibodies and magnetic beads.
- Assessment of binding via Western blotting and immunosorbent assays.
- Analysis of ADAMTS-13 deletion mutants to identify binding domains.
Main Results:
- ADAMTS-13 binds native multimeric VWF with a K(d) of 79 +/- 11 nmol/L without proteolysis.
- Shear-induced VWF unfolding increased ADAMTS-13 binding threefold, leading to VWF cleavage.
- Binding is saturable, time-dependent, reversible, and mediated by domains distal to the ADAMTS-13 spacer, likely thrombospondin-1 repeats.
Conclusions:
- ADAMTS-13 binds to circulating VWF.
- This binding facilitates incorporation into platelet-rich thrombi.
- ADAMTS-13 can cleave shear-unfolded VWF within thrombi.
Related Concept Videos
01:22Formation of the Platelet Plug
The platelet phase, the second stage of hemostasis, commences around 15-20 seconds after an injury. It follows and overlaps with the vascular phase, during which blood vessels constrict to minimize blood loss.
As the injured blood vessel contracts, endothelial cells undergo contraction, revealing collagen fibers in the basement membrane and underlying connective tissue. Furthermore, the plasma membrane of endothelial cells becomes adhesive, preparing the site for platelet adhesion. Platelets...
As the injured blood vessel contracts, endothelial cells undergo contraction, revealing collagen fibers in the basement membrane and underlying connective tissue. Furthermore, the plasma membrane of endothelial cells becomes adhesive, preparing the site for platelet adhesion. Platelets...
01:20Extrinsic and Intrinsic Pathways of Hemostasis
Blood clotting or coagulation involves extrinsic and intrinsic pathways, which ultimately merge into the common pathway, forming a fibrin clot.
The Extrinsic Pathway
The extrinsic pathway of coagulation is typically initiated by tissue damage that exposes blood to tissue factor (TF), a protein released by the damaged tissue cells outside the blood vessels—this interaction with TF triggers biochemical reactions involving specific clotting factors. The key player here is Factor VII, which forms a...
The Extrinsic Pathway
The extrinsic pathway of coagulation is typically initiated by tissue damage that exposes blood to tissue factor (TF), a protein released by the damaged tissue cells outside the blood vessels—this interaction with TF triggers biochemical reactions involving specific clotting factors. The key player here is Factor VII, which forms a...
01:17Intracellular Signaling Affects Focal Adhesions
Integrins act both as extracellular input receivers and as intracellular processing activators. As their name suggests, integrins are entirely integrated into the membrane structure. Their hydrophobic membrane-spanning regions interact with the phospholipid bilayer's hydrophobic region. These membrane receptors provide extracellular attachment sites for effectors like hormones and growth factors. They activate intracellular response cascades when their effectors are bound and active.
Some...
Some...
01:16Vascular Spasm
The vascular phase, also known as vasospasm, is the initial stage of hemostasis, crucial for preventing excessive bleeding when a blood vessel is injured. After a vessel is cut, nerves in the damaged area trigger pain and other sensory impulses. Simultaneously, the smooth muscles in the vessel wall contract, resulting in a vascular spasm. This contraction reduces the vessel's diameter at the injury site, slowing or stopping blood loss through the vessel wall. Vascular spasms typically last for...
01:05Introduction to Hemostasis
Hemostasis is a complex physiological process that prevents excessive bleeding when a blood vessel is injured. It's crucial for maintaining the integrity of the circulatory system, as it ensures that our blood remains fluid while still within the vascular network and yet clots to prevent blood loss upon vessel injury.
The three phases of hemostasis involve many clotting factors present in plasma and several substances released by platelets and injured tissue cells. It is a fast, localized, and...
The three phases of hemostasis involve many clotting factors present in plasma and several substances released by platelets and injured tissue cells. It is a fast, localized, and...
01:24Regulation of Angiogenesis and Blood Supply
Rapidly dividing tumors, embryos, and wounded tissues require more oxygen than usual, lowering the oxygen concentration in the blood. At low oxygen or hypoxic conditions, an oxygen-sensitive transcription factor called the hypoxia-inducible factor 1 or HIF1 is activated. HIF1 is a dimeric protein of alpha (ɑ) and beta (β) subunits. Under optimal oxygen conditions, HIF1β is present in the nucleus while HIF1ɑ remains in the cytosol. HIF1ɑ is hydroxylated by prolyl hydroxylase and factor...