This enzyme is involved in the lacto-N-biose I/galacto-N-biose degradation pathway in the probiotic bacterium Bifidobacterium longum. Differs from EC 22.214.171.124, N-acetylgalactosamine kinase, as it can phosphorylate both N-acetylgalactosamine and N-acetylglucosamine at similar rates. Also has some activity with N-acetyl-D-mannosamine, D-talose and D-mannose as substrate. ATP can be replaced by GTP or ITP but with decreased enzyme activity. Requires a divalent cation, with Mg2+ resulting in by far the greatest stimulation of enzyme activity.