Source:http://linkedlifedata.com/resource/umls/id/C0009547
MSH: Complement activation initiated by the binding of COMPLEMENT C1 to ANTIGEN-ANTIBODY COMPLEXES at the COMPLEMENT C1Q subunit. This leads to the sequential activation of COMPLEMENT C1R and COMPLEMENT C1S subunits. Activated C1s cleaves COMPLEMENT C4 and COMPLEMENT C2 forming the membrane-bound classical C3 CONVERTASE (C4B2A) and the subsequent C5 CONVERTASE (C4B2A3B) leading to cleavage of COMPLEMENT C5 and the assembly of COMPLEMENT MEMBRANE ATTACK COMPLEX.,NCI: The complement system is part of the defense against invading cells and is composed of about twenty different proteins found in the plasma. When activated, complement proteins form a pathway of proteolytic reactions that culminates in the lysis of foreign cells. The complement system also stimulates phagocytosis of foreign cells and an inflammatory response. There are two different complement systems, the classical complement pathway initiated by antibody complexes on the cell surface, and an alternative complement pathway that is initiated withou