C4BP (protein)

C4BP is a protein involved in the complement system. C4BP has a hydra-like structure with a central stalk and seven branching alpha-chains.

Functions
It inhibits the action of C4. It splits C4 convertase and is a cofactor for factor I which cleaves C4b.

C4BP binds necrotic cells and DNA, to clean up after swelling.

It also binds CD40 on B cells which potentiaties proliferation and costimulation.