Complement control proteins are proteins that interact with components of the complement system.
The complement system is tightly regulated by a network of proteins known as "regulators of complement activation (RCA)" that help distinguish target cells as "self" or "non-self." A subset of this family of proteins, complement control proteins (CCP), are characterized by domains of conserved repeats that direct interaction with components of the complement system.[1] These "Sushi" domains have been used to identify other putative members of the CCP family. There are many other RCA proteins that do not fall into this family.
Most CCPs prevent activation of the complement system on the surface of host cells and protect host tissues against damage caused by autoimmunity. Because of this, these proteins play important roles in autoimmune disorders and cancers.[2]