Structure and Function
It is composed of a complex of four complement proteins (C5b, C6, C7, and C8) that bind to the outer surface of the plasma membrane, and many copies of a fifth protein (C9) that hook up to one another, forming a ring in the membrane. C6-C9 all contain a common MACPF domain. This region is homologous to cholesterol-dependent cytolysins from Gram-positive bacteria.
The ring structure formed by C9 is a pore in the membrane that allows free diffusion of molecules in and out of the cell. If enough pores form, the cell is no longer able to survive.
Read more about this topic: Complement Membrane Attack Complex
Famous quotes containing the words structure and, structure and/or function:
“Science is intimately integrated with the whole social structure and cultural tradition. They mutually support one other—only in certain types of society can science flourish, and conversely without a continuous and healthy development and application of science such a society cannot function properly.”
—Talcott Parsons (1902–1979)
“... the structure of a page of good prose is, analyzed logically, not something frozen but the vibrating of a bridge, which changes with every step one takes on it.”
—Robert Musil (1880–1942)
“Literature does not exist in a vacuum. Writers as such have a definite social function exactly proportional to their ability as writers. This is their main use.”
—Ezra Pound (1885–1972)