With TolR probably plays a role in maintaining the position of the peptidoglycan cell wall in the periplasm. Acts as a porin with low permeability that allows slow penetration of small solutes; an internal gate slows down solute passage. Monomer and homodimer. The extracellular loops are most variable in sequence, and in some bacteria confer sensitivity to phage and/or colicins. Non-typeable Haemophilus influenzae (NTHi) is a primary pathogen in otitis media (inflammation of the middle ear). Belongs to the outer membrane OOP (TC 1.B.6) superfamily. OmpA family.