THE MEMBRANE ATTACK COMPLEX OF COMPLEMENT - ASSEMBLY, STRUCTURE AND CYTOTOXIC ACTIVITY

The membrane attack complex of complement is formed by the molecular f usion of the five terminal complement proteins, C5, C6, C7, C8, and C9 . While the assembly process on a target membrane and its modulation b y restriction factors present on host cells is now quite well understo od the molecular details of the architecture of the complex still need much further clarification. This is especially true for the interacti on of the last acting protein C9, which provides the cytotoxic action of the complex, with the precursor C5b-8 complex. Because of this lack of structural details the molecular mechanisms that lead to complemen t-mediated cell death remain cryptic, however, it is hoped that recent advances in controlling the assembly process and in site-specific mod ification of the terminal complement proteins by recombinant DNA techn iques should change this predicament quickly.