O glycosylation

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The O -Glykosylierung (synonym O glycosylation) is a post-translational modification , wherein the carbohydrates (glycosyl) to hydroxyl groups of proteins to form an ether linkage ( O -) are appended.

properties

The O -Glykosylierung is a form of glycosylation in which the glycosyl groups to the side chain of the amino acids serine or threonine in proteins covalently to be connected. It occurs in all living things. In vertebrates, O- glycosylation is used, among other things, in the biosynthesis of proteoglycans (for the extracellular matrix and cell adhesion ), mucins (in the mucus ) and blood group proteins . In contrast to O -glycosylation, in N -glycosylation the glycosyl group is transferred to the amino group of the side chain of the amino acid asparagine .

biosynthesis

The synthesis of O -glycosylation usually takes place in the Golgi apparatus . The first carbohydrate on the hydroxyl group of a glycated serine or threonine is either an N -acetylglucosamine (GlcNAc), an N -acetylgalactosamine (GalNAc), a glucose (Glc), a mannose (Man) or a fucose (Fuc). A GlcNAc is attached by the O-GlcNAc transferase ( EC  2.4.1.255 ). The linkage of GalNAc occurs mainly in mucins, is the most common form of O- glycosylation and is catalyzed by UDP-N-acetyl-D-galactosamine: polypeptide N-acetylgalactosaminyl transferase ( O-GalNAc transferase , EC  2.4.1.41 ). Mannose is the pomt1 and protein O -Mannosyltransferase 2 linked ( mannosylation ). Fucose is coupled by the GDP-fucose protein- O- fucosyltransferase 1 ( fucosylation ).

Genetic defects

Genetic defects in genes of O -Glykosylierung are associated with more than 20 diseases, including multiple exostoses , the progeroide variant of Ehlers-Danlos syndrome , progeria , familial tumoral calcinosis , screw pelvic dysplasia , Walker-Warburg syndrome , spondylocostale dysostosis type 3 and Peters -Plus syndrome .

literature

Individual evidence

  1. ^ A b c K. Drickamer, ME: Taylor Introduction to Glycobiology. 2nd edition. Oxford University Press, 2006. ISBN 978-0-19-928278-4 .
  2. ↑ L. Zhang, KG Ten Hagen: The cellular microenvironment and cell adhesion: a role for O-glycosylation. In: Biochemical Society Transactions . Volume 39, number 1, January 2011, pp. 378-382, doi : 10.1042 / BST0390378 , PMID 21265808 , PMC 3378992 (free full text).
  3. ^ E. Tian, ​​KG Ten Hagen: Recent insights into the biological roles of mucin-type O-glycosylation. In: Glycoconjugate journal. Volume 26, Number 3, April 2009, pp. 325-334, doi : 10.1007 / s10719-008-9162-4 , PMID 18695988 , PMC 2656418 (free full text).
  4. ↑ a b B. Cylwik, K. Lipartowska, L. Chrostek, E. Gruszewska: Congenital disorders of glycosylation. Part II. Defects of protein O-glycosylation. In: Acta biochimica Polonica. Volume 60, Number 3, 2013, pp. 361-368, PMID 24051442 .
  5. ^ EP Bennett, U. Mandel, H. Clausen, TA Gerken, TA Fritz, LA Tobacco: Control of mucin-type O-glycosylation: a classification of the polypeptide GalNAc-transferase gene family. In: Glycobiology. Volume 22, Number 6, June 2012, pp. 736-756, doi : 10.1093 / glycob / cwr182 , PMID 22183981 , PMC 3409716 (free full text).
  6. ^ DT Tran, KG Ten Hagen: Mucin-type O-glycosylation during development. In: Journal of Biological Chemistry . Volume 288, Number 10, March 2013, pp. 6921-6929, doi : 10.1074 / jbc.R112.418558 , PMID 23329828 , PMC 3591602 (free full text).