|
skos:definition |
MSH: Complement activation initiated by the interaction of microbial ANTIGENS with COMPLEMENT C3B. When COMPLEMENT FACTOR B binds to the membrane-bound C3b, COMPLEMENT FACTOR D cleaves it to form alternative C3 CONVERTASE (C3BBB) which, stabilized by COMPLEMENT FACTOR P, is able to cleave multiple COMPLEMENT C3 to form alternative C5 CONVERTASE (C3BBB3B) leading to cleavage of COMPLEMENT C5 and the assembly of COMPLEMENT MEMBRANE ATTACK COMPLEX.,NCI: The complement system of plasma proteins is an important part of the immune system that forms a cascade of factors that lyses foreign cells. There are two branches of the complement system, the classical pathway that is initiated by antibody-antigen complexes on a cell and the alternative pathway that is antibody independent. The ultimate result in either pathway is the creation of the membrane attack complex, a large pore in the cell membrane that results in cell lysis. The alternative pathway starts with the spontaneous conversion of C3 to an active protease. C
|
