alpha-D-Glc-(1->3)-[L-alpha-D-Hep-(1->7)]-4-O-PO3(2-)-L-alpha-D-Hep-(1->3)-4-O-PO3(2-)-L-alpha-D-Hep-(1->5)-[alpha-Kdo-(2->4)]-alpha-Kdo-(2->6)-lipid A + UDP-alpha-D-galactose = alpha-D-Gal-(1->6)-alpha-D-Glc-(1->3)-[L-alpha-D-Hep-(1->7)]-4-O-PO3(2-)-L-alpha-D-Hep-(1->3)-4-O-PO3(2-)-L-alpha-D-Hep-(1->5)-[alpha-Kdo-(2->4)]-alpha-Kdo-(2->6)-lipid A + UDP + H(+) — reaction