Complement component 2

Complement Component 2

Structure of Complement Component 2

Complement Component 2 (C2) is a protein of the complement system, which is part of the innate immune system. The complement system is a group of proteins that play a crucial role in immune response by enhancing the ability of antibodies and phagocytic cells to clear pathogens from an organism. C2 is a key component in the classical pathway of complement activation.

Structure

Complement Component 2 is a serine protease that is encoded by the C2 gene in humans. The protein is synthesized as a single-chain precursor and is cleaved into two fragments, C2a and C2b, upon activation. The structure of C2 is characterized by several domains that are important for its function in the complement cascade.

Function

C2 plays a pivotal role in the classical pathway of complement activation. Upon activation by the C1 complex, C2 is cleaved by C1s into C2a and C2b. The C2a fragment combines with C4b to form the C3 convertase (C4b2a), which is essential for the cleavage of C3 into C3a and C3b. This step is crucial for the amplification of the complement response and the opsonization of pathogens.

Clinical Significance

Deficiencies in Complement Component 2 can lead to increased susceptibility to infections and autoimmune diseases. C2 deficiency is a rare genetic disorder that can result in recurrent bacterial infections and is associated with conditions such as systemic lupus erythematosus (SLE).

Related Pages

• Complement system
• Classical pathway
• C3 convertase
• Immune system
• Systemic lupus erythematosus