C4bps

C4BP is a protein that plays a crucial role in the complement system, a part of the innate immune system. It is composed of eight identical subunits, each containing a C4b-binding domain and a short consensus repeat domain. The primary function of C4BP is to regulate the activation of the complement cascade by inhibiting the formation of the C3 convertase. It achieves this by binding to the C4b component of the C3 convertase, thereby accelerating its dissociation and rendering it inactive. This regulatory mechanism prevents excessive and potentially damaging complement activation. C4BP is found in plasma and on cell surfaces. Its expression is regulated by inflammatory cytokines, and it is particularly important in preventing autoimmune damage by limiting the complement-mediated destruction of host cells. Dysregulation of C4BP activity has been implicated in various inflammatory and autoimmune diseases.