 The core complex of the scaffold is composed of 14 copies of VirB7, VirB9, and VirB10 which form a cylindrical channel that spans both membranes and connects the cytoplasm to the extracellular space.A single protein, VirB10 is integral in both the inner and outer membranes.It inserts into the outer membrane using an α-helical barrel structure which helps form a channel between the two membranes.