title: Complex N-glycans: the story of the "yellow brick road".
abstract: The synthesis of complex asparagine-linked glycans (N-glycans) involves a multi-step process that starts with a five mannose N-glycan structure: [Manα1-6(Manα1-3)Manα1-6][Manα1-3]-R where R = Manβ1-4GlcNAcβ1-4GlcNAcβ1-Asn-protein. N-acetylglucosaminyltransferase I (GlcNAc-TI) first catalyzes addition of GlcNAc in β1-2 linkage to the Manα1-3-R terminus of the five-mannose structure. Mannosidase II then removes two Man residues exposing the Manα1-6 terminus that serves as a substrate for GlcNAc-T II and addition of a second GlcNAcβ1-2 residue. The resulting structure is the complex N-glycan: GlcNAcβ1-2Manα1-6(GlcNAcβ1-2Manα1-3)-R. This structure is the precursor to a large assortment of branched complex N-glycans involving four more N-acetylglucosaminyltransferases. This short review describes the experiments (done in the early 1970s) that led to the discovery of GlcNAc-TI and II.
authors.affiliation: Molecular Structure and Function Program, Hospital for Sick Children, 555 University Avenue, Toronto, ON, Canada, M5G 1X8, harry@sickkids.ca.
authors.forename: Harry
authors.initials: H
authors.lastname: Schachter
mesh_terms: D000818:Animals; D006801:Humans; D008361:Mannosidases / Q000378:metabolism; D017351:N-Acetylglucosaminyltransferases / Q000378:metabolism; D011134:Polysaccharides / Q000096:biosynthesis*
chemical_list: D011134:Polysaccharides; D017351:N-Acetylglucosaminyltransferases; D008361:Mannosidases