Here,pore formation is not a prerequisite for translocation,nor is there any need to preform a complex since cargo and carrier are on opposite sides of the membrane.form this,a very interesting scenario emerges.guanidinium-rich carriers enter the membrane bound to one ion and upon reaching the other side,exchange anionic cargo.the new complex crosses back to extract the cargo.the idea that guanidinium-rich species might "reach across"membranes to withdraw anions(termed interface-directed translocation)has been demonstrated with small cargoes