Related Experiment Video

Updated: Sep 30, 2026

Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay
13:08

Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay

Published on: September 9, 2012

Molecular characterization of an extended binding site for coagulation factor Va in the positive exosite of activated

Andrew J Gale1, Alexander Tsavaler, John H Griffin

  • 1Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, USA. agale@scripps.edu

The Journal of Biological Chemistry
|June 14, 2002
PubMed

Insights

Activated protein C (APC) inhibits blood coagulation by inactivating factors Va and VIIIa. Key residues Lys193, Arg229, and Arg230 on APC are crucial for binding and cleaving factor Va, defining its binding site.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Hematology

Background:

  • Activated protein C (APC) is a crucial anticoagulant serine protease.
  • APC regulates blood coagulation by inactivating factors Va and VIIIa.
  • Understanding APC's interaction with factor Va is vital for thrombosis research.

Purpose of the Study:

  • To identify specific residues in APC's positive exosite responsible for binding factor Va (FVa).
  • To elucidate the role of these residues in the inactivation of FVa by APC.
  • To characterize the FVa binding site on APC.

Main Methods:

  • Site-directed mutagenesis was employed to alter 18 residues in APC's surface loops.
  • Mutant APC proteins were purified and characterized.
  • The inactivation of FVa by mutant APC was assessed.

Main Results:

  • Three APC residues (Lys193, Arg229, Arg230) were identified as major contributors to FVa binding.
  • Four additional residues (Lys191, Lys192, Asp214, Glu215) showed significant minor contributions.
  • These residues primarily mediate APC cleavage at Arg506 on FVa.

Conclusions:

  • An extensive FVa binding site on APC's positive exosite has been defined.
  • This site is critical for APC's anticoagulant function through FVa inactivation.
  • The findings advance our understanding of coagulation regulation and potential therapeutic targets.

More Related Videos

Helical Organization of Blood Coagulation Factor VIII on Lipid Nanotubes12:24

Helical Organization of Blood Coagulation Factor VIII on Lipid Nanotubes

Published on: June 3, 2014

Comprehensive Analysis of Procoagulant Platelets Exhibiting Features of Necrosis, Apoptosis and Platelet Activation04:37

Comprehensive Analysis of Procoagulant Platelets Exhibiting Features of Necrosis, Apoptosis and Platelet Activation

Published on: May 23, 2025

Related Concept Videos

Extrinsic and Intrinsic Pathways of Hemostasis01:20

Extrinsic 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...
Clot Retraction and Fibrinolysis01:16

Clot Retraction and Fibrinolysis

After a fibrin clot is formed, the next step is clot retraction, a vital process facilitated by platelet contractile proteins, such as actin and myosin. These proteins pull the fibrin strands closer together and condense the clot. This action reduces the size of the clot, creating a smaller, denser structure that effectively seals off the damaged vessel. Clot retraction consolidates the clot and helps with wound healing by bringing the edges of the damaged blood vessel closer together.
Coagulation01:09

Coagulation

The coagulation phase is a critical part of the body's process to prevent blood loss following injury to blood vessels. It involves chemical reactions that form a clot to seal the injured area. The clotting process begins shortly after injury, within 15-20 seconds for severe damage and 1-2 minutes for minor injuries.
During the coagulation phase, clotting factors, or procoagulants, play a vital role in initiating and progressing the coagulation cascade. This cascade is a series of reactions...
Coagulation01:06

Coagulation

Colloidal solids are solid particles suspended in solution. They are usually negatively charged, attracting a compact primary layer of positively charged ions, which attract more counterions to form an electrical double layer. Electrostatic repulsion between the charged double layers prevents the particles from colliding, stabilizing the colloids. These solids are often undesirable because they can contain toxins that are difficult to remove. Coagulation is a technique that helps aggregate and...
Anticoagulant Drugs: Low-Molecular-Weight Heparins01:30

Anticoagulant Drugs: Low-Molecular-Weight Heparins

Hemostasis is a crucial process that prevents excessive blood loss from damaged blood vessels. It involves various mechanisms such as vasoconstriction, platelet adhesion and activation, and fibrin formation. The importance of each mechanism depends on the type of vessel injury. In contrast, thrombosis is the abnormal formation of a blood clot within the blood vessels, leading to potential complications if the clot obstructs blood flow. Thrombosis can be caused by increased coagulability of the...
Formation of the Platelet Plug01:22

Formation 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...