Related Experiment Video
Updated: May 8, 2026

06:45
Dissecting Multi-protein Signaling Complexes by Bimolecular Complementation Affinity Purification (BiCAP)
Published on: June 15, 2018
Restoring the procofactor state of factor Va-like variants by complementation with B-domain peptides
Matthew W Bunce1, Mettine H A Bos1, Sriram Krishnaswamy2
1From the Division of Hematology, The Children's Hospital of Philadelphia and.
The Journal of Biological Chemistry
|September 10, 2013
Summary
The B-domain of coagulation factor V (FV) inhibits its own activation. A basic region (BR) fragment binds to FV, blocking activation and restoring the inactive procofactor state.
Area of Science:
- Biochemistry
- Molecular Biology
- Hematology
Background:
- Coagulation factor V (FV) is a procofactor activated to FVa.
- The FV B-domain inhibits procofactor activity.
- Conserved sequences in the B-domain are crucial for autoinhibition.
Purpose of the Study:
- To elucidate the mechanism of FV autoinhibition by the B-domain.
- To investigate the role of the B-domain's basic region (BR) in FV regulation.
Main Methods:
- Utilized recombinant B-domain fragments.
- Assessed binding affinity of BR fragments to FV(a) variants.
- Investigated inhibition of procoagulant function.
- Studied competition with FXa for FV(a) binding.
- Analyzed effects of limited proteolysis at Arg(1545).
Main Results:
- A BR fragment binds with high affinity to FV(a) variants with an intact acidic region.
- The BR inhibits procoagulant function, restoring the procofactor state.
- BR competes with FXa for FV(a) binding.
- Proteolysis at Arg(1545) disrupts BR binding, promoting FVa-FXa association.
Conclusions:
- The B-domain stabilizes inactive FV through interactions involving conserved sequences.
- Limited proteolysis of the B-domain releases inhibition, facilitating FV activation.
- This reveals a mechanism for regulating FV activity through B-domain destabilization.
Related Concept Videos
Protein Complexes with Interchangeable Parts
Groups of proteins may form a complex where each protein in this complex has a different role in the overall execution of the complex’s function. Often some of the proteins in the complex can be replaced by a closely related variant to give a complex that contains many of the same components yet is functionally distinct.
The SCF ubiquitin ligase is a protein complex of five individual proteins. This complex attaches ubiquitin to other target proteins to mark them for degradation. In order to...
The SCF ubiquitin ligase is a protein complex of five individual proteins. This complex attaches ubiquitin to other target proteins to mark them for degradation. In order to...
Coat Assembly and GTPases
Vesicles incorporate different coat protein subunits in different cell locations, which changes the properties of the coat, such as the shape and geometry of the transport vesicles. Thus, vesicle coat proteins also play a significant role in cargo selection.
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Cofactors and Coenzymes
Enzymes require additional components for proper function. There are two such classes of molecules: cofactors and coenzymes. Cofactors are metallic ions and coenzymes are non-protein organic molecules. Both of these types of helper molecule can be tightly bound to the enzyme or bound only when the substrate binds.
Cofactors and Coenzymes
Enzymes are proteins made of amino acids. The functional group of each constituent amino acid catalyzes a wide variety of chemical reactions via ionic interactions or acid-base reactions. However, amino acids cannot catalyze oxidation-reduction and group transfer reactions and need to be aided by non-protein components called cofactors. Cofactors are also referred to as the chemical teeth of an enzyme.
Cofactors can be metallic ions or organic molecules called coenzymes. These types of helper...
Cofactors can be metallic ions or organic molecules called coenzymes. These types of helper...
Cofactors and Coenzymes
Enzymes require additional components for proper function. There are two such classes of molecules: cofactors and coenzymes. Cofactors are metallic ions and coenzymes are non-protein organic molecules. Both of these types of helper molecule can be tightly bound to the enzyme or bound only when the substrate binds.
Protein Complex Assembly
Proteins can form homomeric complexes with another unit of the same protein or heteromeric complexes with different types. Most protein complexes self-assemble spontaneously via ordered pathways, while some proteins need assembly factors that guide their proper assembly. Despite the crowded intracellular environment, proteins usually interact with their correct partners and form functional complexes.
Many viruses self-assemble into a fully functional unit using the infected host cell to...
Many viruses self-assemble into a fully functional unit using the infected host cell to...

