 Due to the wide variety of type IV secretion systems in both origin and function, it is difficult to state much mechanistically about the group as a whole.In general, after DNA is packaged in a conjugative system it is recruited by ATPase analogues to the VirD4 coupling protein, then translocated through the pilus.In "A. tumefaciens" specifically, the DNA passes through a characterized chain of enzymes before reaching the pilus.