Binding of C3 molecules to membranes via the SH-residue generated by the cleavage of a thioester bond can initiate complement activation.

Dithiopyridine (DTP)-dipalmitoylphosphatidylethanolamine (DTP-DPPE) was incorporated into liposome membranes to prepare DTP-liposomes. The DTP-liposomes could be lysed by reaction with the alternative complement pathway of any kind of serum tested. Activation of the alternative complement pathway has been shown to be mediated by the binding of C3 molecules to DTP on the liposomes via the SH-residue generated by the cleavage of thioester bond in the alpha-chain of the molecules.