Metabolism of Vertebrate Amino Sugars with N-Glycolyl Groups-GLYCOLYLHEXOSAMINESINTOMAMMALIANGLYCANSBY

-acetylmannos-amine kinase-deficient cells, we confirm that conversion ofGalNGc into Neu5Gc depends on this key enzyme of sialic acidbiosynthesis.Furthermore,wedemonstratebymassspectrometrythatthemetabolicintermediatesUDP-GalNGcandUDP-GlcNGcserve as substrates for assembly of most major classes of cellularglycans. We show for the first time incorporation of GalNGc andGlcNGcintochondroitin/dermatansulfatesandheparansulfates,respectively. As demonstrated by structural analysis,