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.[1] To be specific, glucosamine-6-phosphate is synthesized from fructose 6-phosphate and glutamine[2] as the first step of the hexosamine biosynthesis pathway.[3] The end-product of this pathway is UDP-GlcNAc, which is then used for making glycosaminoglycans, proteoglycans, and glycolipids.[4]

UDP-GlcNAc is extensively involved in intracellular signaling as a substrate for O-linked N-acetylglucosamine transferases (OGTs) to install the O-GlcNAc post-translational modification in a wide range of species. It is also involved in nuclear pore formation and nuclear signalling. OGTs and OG-ases play an important role in the structure of the cytoskeleton. In mammals, there is enrichment of OGT transcripts in the pancreas beta-cells, and UDP-GlcNAc is thought to be part of the glucose sensing mechanism. There is also evidence that it plays a part in insulin sensitivity in other cells. In plants, it is involved in the control of gibberellin production.[5]

Clostridium novyi type A alpha-toxin is an O-linked N-actetylglucosamine transferase acting on Rho proteins and causing the collapse of the cytoskeleton.

References

  1. ^ Roseman S (2001). "Reflections on glycobiology". The Journal of Biological Chemistry. 276 (45): 41527–42. doi:10.1074/jbc.R100053200. PMID 11553646.
  2. ^ Sudhamoy Ghosh, Blumenthal HJ, Davidson E, Roseman S (1960-05-01). "Glucosamine Metabolism". Journal of Biological Chemistry. 235 (5): 1265–73. doi:10.1016/S0021-9258(18)69397-4. PMID 13827775.
  3. ^ International Union of Biochemistry and Molecular Biology
  4. ^ Milewski S, Gabriel I, Olchowy J (2006). "Enzymes of UDP-GlcNAc biosynthesis in yeast". Yeast. 23 (1): 1–14. doi:10.1002/yea.1337. PMID 16408321.
  5. ^ Hanover JA (2001). "Glycan-dependent signaling: O-linked N-acetylglucosamine". The FASEB Journal. 15 (11): 1865–1876. CiteSeerX 10.1.1.324.6370. doi:10.1096/fj.01-0094rev. PMID 11532966.