C4bC2a

C4bC2a is a protein complex that plays a crucial role in the complement system, a part of the innate immune system. It is formed when the C4b protein binds to the C2a fragment. This complex is known as the C3 convertase of the classical and lectin pathways of complement activation.

The formation of C4bC2a is a key step in the amplification cascade of the complement system. Once formed, its primary function is to cleave the C3 protein into smaller fragments, C3a and C3b. These fragments then initiate further downstream events in complement activation. C3b, in particular, can bind to microbial surfaces or immune complexes, marking them for destruction by phagocytic cells. C3a acts as an anaphylatoxin, contributing to inflammation and attracting immune cells to the site of infection.

The generation of C4bC2a is tightly regulated to prevent damage to host tissues. Its activity is controlled by various complement regulatory proteins. Dysregulation of C4bC2a formation or function can lead to various immune-related disorders. Understanding the structure and function of C4bC2a is therefore important for comprehending immune responses and developing therapeutic strategies for complement-mediated diseases.