Uridine diphosphate N-acetylglucosamine or UDP-GlcNAc is a nucleotide sugar and a coenzyme in metabolism. It is used by glycosyltransferases to transfer N-acetylglucosamine residues to substrates. D-Glucosamine is made naturally in the form of glucosamine-6-phosphate, and is the biochemical precursor of all nitrogen-containing sugars. To be specific, glucosamine-6-phosphate is synthesized from fructose 6-phosphate and glutamine as the first step of the hexosamine biosynthesis pathway. The end-product of this pathway is UDP-GlcNAc, which is then used for making glycosaminoglycans, proteoglycans, and glycolipids.