C7 recruitment of C7 results in a weak association of C5b:C6:C7 with the target cell membrane, through a poorly characterized molecular mechanism (Muller -Eberhard et al. 1986).
C5b and C6 remains loosely bound to C3b until C5b binds to C7 and induces it to undergo a hydrophilic-amphiphilic transition. Hydrophobic binding regions for phospholipid are thereby exposed, and the trimolecular complex is endowed with a metastable membrane binding site. Membranebound
C5b-7 inflicts no harm on a cell but marks it for further assault.