by National Eye Institute The complement membrane attack complex is a pore that inserts into the cell membrane. The complex is formed by up to 18 C9 subunits (purple), the C5, C6, and C7 subunits (various shades of green), and the C8-alpha, C8-beta, and C8-gamma subunits (shades of red). Side (left) and Top (center) views show...