Lpt3 and Lpt6 exhibit LOS HepII 3- and 6-phosphoethanolamine transferase activities, respectively. (A) Dot blot analyses of Lpt3-His6 and Lpt6-His6 reactions (rxns) with N. meningitidis galE lpt3 de-O-Ac LOS in the absence or presence of 1 mg ml−1 phosphatidylethanolamine, using HepII 3-PEtn-specific MAb L3B5 for Lpt3-His6 reactions and HepII 6-PEtn-specific MAb L2-16 for Lpt6-His6 reactions. (B and C) Dot blot analyses of Lpt3-His6 and Lpt6-His6 reactions with N. meningitidis MC58 galE lpt3 LOS and de-O-Ac LOS, using MAb L3B5 (B) and MAb L2-16 (C), respectively. Negative controls were N. meningitidis MC58 galE lpt3 LOS and de-O-Ac LOS, 3-PEtn controls were N. meningitidis MC58 galE LOS and de-O-Ac LOS, and 6-PEtn controls were N. meningitidis 89I galE LOS and de-O-Ac LOS. Note that MAb L3B5 does not react in Lpt6-His6 reactions and MAb L2-16 does not react in Lpt3-His6 reactions.