Identification and characterization of N-acetylglucosamine-6-O-sulfate-specific β1,4-galactosyltransferase in human colorectal mucosa

6-Sulfo-sialyl Lewis X structure is attributable to recognition between lymphocytes and high endothelial venules. However, the biosynthetic pathway still remains unclear. We found that a β-galactosyltransferase (βGalT) in human colorectal mucosa preferentially acts on GlcNAc-6-O-sulfate (6S-GN). 6S-GN:β4GalT was partially purified by UDP-hexanolamine-Sepharose and asialo-agalacto-ovomucin-Sepharose chromatographies. The optimum pH of this enzyme was found to be 6.5–7.5 and the Michaelis constants for 6S-GN and UDP-Gal were 0.43 mM and 16 μM, respectively. The enzymatic activity was dependent on divalent cations and the substrate specificity was not affected by α-lactalbumin. This is the first demonstration of the occurrence of 6S-GN:β4GalT.