Outer membrane channel protein allowing the entry of N-acetylneuraminic acid (Neu5Ac, the most abundant sialic acid on host cell surfaces) into the bacteria. NanC proteins form high-conductance channels which are open at low membrane potentials and which have a weak anion selectivity (By similarity). Monomer. Belongs to the oligogalacturonate-specific porin KdgM (TC 1.B.35) family. NanC subfamily. Truncated N-terminus. Truncated N-terminus.