Related Experiment Video

Updated: Jun 24, 2026

Stability and Structure of Bat Major Histocompatibility Complex Class I with Heterologous β2-Microglobulin
11:17

Stability and Structure of Bat Major Histocompatibility Complex Class I with Heterologous β2-Microglobulin

Published on: March 10, 2021

The crystal structure of cobra venom factor, a cofactor for C3- and C5-convertase CVFBb

Vengadesan Krishnan1, Karthe Ponnuraj, Yuanyuan Xu

  • 1University of Alabama at Birmingham, Birmingham, AL 35294, USA.

Structure (London, England : 1993)
|April 17, 2009
PubMed

Insights

Cobra venom factor (CVF), a complement C3b analog, forms a stable CVFBb complex. Its crystal structure reveals domain positioning crucial for factor B binding and C3 convertase formation.

Area of Science:

  • Immunology
  • Structural Biology
  • Biochemistry

Background:

  • Cobra venom factor (CVF) mimics human complement component C3b, the active fragment of C3.
  • CVF interacts with factor B and D to form a stable CVFBb complex, a potent C5 convertase.
  • Understanding CVF's structure is key to elucidating its mechanism in complement system activation.

Purpose of the Study:

  • To determine the crystal structure of cobra venom factor (CVF).
  • To analyze the structural basis for CVF's interaction with factor B.
  • To understand CVF's role in complement convertase formation.

Main Methods:

  • Isolation of CVF from Naja naja kouthia venom.
  • X-ray crystallography to solve the CVF structure at 2.6 Å resolution.
  • Structural comparison with human complement component C3b.

Main Results:

  • The crystal structure of CVF was determined, revealing it as an intermediate between C3b and C3c.
  • CVF lacks the TED domain but retains the CUB domain in a position identical to C3b.
  • The CUB and C345c domains of CVF are positioned to facilitate factor B binding, crucial for C3 convertase assembly.

Conclusions:

  • The determined CVF structure provides insights into its function as a complement activator.
  • The specific positioning of CVF's CUB and C345c domains is vital for factor B interaction.
  • This structural information aids in understanding the molecular mechanisms of complement system regulation.

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

Use of Viral Entry Assays and Molecular Docking Analysis for the Identification of Antiviral Candidates against Coxsackievirus A1606:03

Use of Viral Entry Assays and Molecular Docking Analysis for the Identification of Antiviral Candidates against Coxsackievirus A16

Published on: July 15, 2019

Related Concept Videos

Crystal Field Theory - Octahedral Complexes02:58

Crystal Field Theory - Octahedral Complexes

Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
Cofactors and Coenzymes01:24

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 and Coenzymes01:27

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 Coenzymes01:27

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.
Antibody Structure01:10

Antibody Structure

Overview
Antibodies, also known as immunoglobulins (Ig), are essential players of the adaptive immune system. These antigen-binding proteins are produced by B cells and make up 20 percent of the total blood plasma by weight. In mammals, antibodies fall into five different classes, which each elicits a different biological response upon antigen binding.
The Y-Shaped Structure of Antibodies Consists of Four Polypeptide Chains
Antibodies consist of four polypeptide chains: two identical heavy...
Antibody Structure01:10

Antibody Structure

Overview
Antibodies, also known as immunoglobulins (Ig), are essential players of the adaptive immune system. These antigen-binding proteins are produced by B cells and make up 20 percent of the total blood plasma by weight. In mammals, antibodies fall into five different classes, which each elicits a different biological response upon antigen binding.
The Y-Shaped Structure of Antibodies Consists of Four Polypeptide Chains
Antibodies consist of four polypeptide chains: two identical heavy...