Completed LPS molecules are transported to the outer leaflet of the outer membrane from the periplasmic side of the inner membrane by a consortium of Lpt proteins. The inner membrane LptB₂CFG complex uses cytoplasmic ATP, to energise entire mechanism of transport. LptA is a periplasmic protein that shuttles the LPS to the outer membrane. The LptDE complex places the LPS in the outer leaflet. The precise biochemical functions of these proteins is not known, function is infered by deletion mutations.