Studies on the interaction between vitamin K-dependent protein S and complement regulator C4b-binding protein: localization of binding sites and identification of a possible function of the complex.
Complement is a cascade-like system that is part of the innate immune defence. It is an explosive system, potentially harmful also for the host cells, and needs to be strictly regulated. An important down-regulator of complement is C4b-binding protein (C4BP). C4BP contains two different types of subunits, seven identical a-chains and one unique P-chain. The alpha-chains bind to C4b, C4BP's target