Related Experiment Video
Updated: Aug 7, 2026
13:00
Engineering Antiviral Agents via Surface Plasmon Resonance
Published on: June 14, 2022
Defining the CD59-C9 binding interaction
Yuxiang Huang1, Fei Qiao, Ruben Abagyan
1Department of Microbiology and Immunology, Medical University of South Carolina, South Carolina 29403, USA.
The Journal of Biological Chemistry
|July 18, 2006
Summary
Researchers identified a specific 6-residue sequence in complement protein C9 that acts as the primary binding site for CD59. This finding clarifies how CD59 regulates the formation of the membrane attack complex (MAC).
Area of Science:
- Immunology
- Complement System Biology
Background:
- CD59 is a crucial membrane glycoprotein regulating the formation of the cytolytic membrane attack complex (MAC, or C5b-9).
- CD59 functions by binding to C8 (alpha chain) and C9 during MAC assembly, inhibiting its completion on host cell membranes.
Purpose of the Study:
- To pinpoint the precise region of human C9 responsible for CD59 recognition.
- To elucidate the interaction site of CD59 on C8alpha and C9.
Main Methods:
- Peptide screens and binding assays were employed to identify CD59 interaction domains.
- Functional assays and computer modeling, including docking studies, were utilized to analyze CD59-protein interactions.
Main Results:
- A 6-residue sequence (residues 365-371) in human C9 was identified as the primary CD59 recognition domain.
- Both C8alpha and C9 appear to bind to a similar or overlapping site on CD59.
- CD59-peptide docking models suggest C9 binds to a hydrophobic pocket on CD59.
Conclusions:
- The study precisely maps the CD59 recognition site on C9, advancing understanding of MAC regulation.
- The findings provide a molecular basis for CD59's inhibitory function in the complement cascade.
- This detailed interaction knowledge could inform therapeutic strategies targeting complement-mediated damage.
Related Concept Videos
02:18The Equilibrium Binding Constant and Binding Strength
The equilibrium binding constant (Kb) quantifies the strength of a protein-ligand interaction. Kb can be calculated as follows when the reaction is at equilibrium:
01:31Immunoglobulin-like Cell Adhesion Molecules
Immunoglobulin-like cell adhesion molecules or Ig-CAMs are a versatile group of cell surface glycoproteins belonging to the immunoglobulin protein superfamily. Ig-CAMs possess the characteristic immunoglobulin protein domains and other domains such as the fibronectin type III domain. The Ig domains are glycosylated to varying degrees in different Ig-CAMs.
Ig-CAMs exhibit either homophilic binding (to other Ig-CAMs) or heterophilic binding (to other ligands such as integrins). While most Ig-CAMs...
Ig-CAMs exhibit either homophilic binding (to other Ig-CAMs) or heterophilic binding (to other ligands such as integrins). While most Ig-CAMs...
00:49Ligand Binding and Linkage
Allosteric proteins have more than one ligand binding site; the binding of a ligand to any of these sites influences the binding of ligands to the other sites. When a protein is allosteric, its binding sites are called coupled or linked. In the case of enzymes, the site that binds to the substrate is known as the active site and the other site is known as the regulatory site. When a ligand binds to the regulatory site, this leads to conformational changes in the protein that can influence the...