Outer membrane channel protein allowing the entry of N-acetylneuraminic acid (Neu5Ac, the most abundant sialic acid on host cell surfaces) into the bacteria (Probable). NanC proteins form high-conductance channels which are open at low membrane potentials and which have a weak anion selectivity. Monomer. Induced by N-acetylneuraminate and modulated by N-acetylglucosamine. This regulation occurs via the NanR and NagC regulators. NanC expression is also activated by the regulators cyclic AMP-catabolite activator protein, OmpR, and CpxR. Belongs to the oligogalacturonate-specific porin KdgM (TC 1.B.35) family. NanC subfamily. Extended N-terminus.