title: Promiscuous activity of ER glucosidase II discovered through donor specificity analysis of UGGT.
abstract: In glycoprotein quality control system in the endoplasmic reticulum (ER), UGGT (UDP-glucose:glycoprotein glucosyltransferase) and glucosidase II (G-II) play key roles. UGGT serves as a glycoprotein folding sensor by virtue of its unique specificity to glucosylate glycoproteins at incompletely folded stage. By using various UDP-Glc analogues, we first analyzed donor specificity of UGGT, which was proven to be rather narrow. However, marginal activity was observed with UDP-galactose and UDP-glucuronic acid as well as with 3-, 4- and 6-deoxy glucose analogues to give corresponding transfer products. Intriguingly, G-II smoothly converted all of them back to Man(9)GlcNAc(2), providing an indication that G-II has a promiscuous activity as a broad specificity hexosidase.
authors.affiliation: RIKEN Advanced Science Institute, Wako, Saitama 351-0198, Japan. miyagawa.atsushi@nitech.ac.jp
authors.forename: Atsushi
authors.initials: A
authors.lastname: Miyagawa
authors.forename: Kiichiro
authors.initials: K
authors.lastname: Totani
authors.forename: Ichiro
authors.initials: I
authors.lastname: Matsuo
authors.forename: Yukishige
authors.initials: Y
authors.lastname: Ito
mesh_terms: D000818:Animals; D037281:Calnexin / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000201:enzymology*; D005964:Glucosyltransferases / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D009844:Oligosaccharides / Q000096:biosynthesis / Q000737:chemistry; D017510:Protein Folding; D013379:Substrate Specificity; D014531:Uridine Diphosphate Galactose / Q000737:chemistry / Q000378:metabolism*; D014535:Uridine Diphosphate Glucuronic Acid / Q000737:chemistry / Q000378:metabolism*; D000520:alpha-Glucosidases / Q000737:chemistry / Q000378:metabolism*
chemical_list: D009844:Oligosaccharides; C477742:mannosyl(6)-N-acetyl(2)glucose; D037281:Calnexin; D014535:Uridine Diphosphate Glucuronic Acid; D014531:Uridine Diphosphate Galactose; D005964:Glucosyltransferases; C072423:mannosylglycoprotein 1,3-glucosyltransferase; C034251:4-nitrophenyl-alpha-glucosidase; D000520:alpha-Glucosidases