Involved in the assembly of lipopolysaccharide (LPS). Required for the translocation of LPS from the inner membrane to the outer membrane. Facilitates the transfer of LPS from the inner membrane to the periplasmic protein LptA. Could be a docking site for LptA. Component of the lipopolysaccharide transport and assembly complex. Interacts with LptA and the LptBFG transporter complex. Belongs to the LptC family.