title: Selective Manipulation of Discrete Mannosidase Activities in the Endoplasmic Reticulum by Using Reciprocally Selective Inhibitors.
abstract: Within the endoplasmic reticulum, immature glycoproteins are sorted into secretion and degradation pathways through the sequential trimming of mannose residues from Man9GlcNAc2to Man5GlcNAc2by the combined actions of assorted α-1,2-mannosidases. It has been speculated that specific glycoforms encode signals for secretion and degradation. However, it is unclear whether the specific signal glycoforms are produced by random mannosidase action or are produced regioselectively in a sequenced manner by specific α-1,2-mannosidases. Here, we report the identification of a set of selective mannosidase inhibitors and development of conditions for their use that enable production of distinct pools of Man8GlcNAc2isomers from a structurally defined synthetic Man9GlcNAc2substrate in an endoplasmic reticulum fraction. Glycan processing analysis with these inhibitors provides the first biochemical evidence for selective production of the signal glycoforms contributing to traffic control in glycoprotein quality control.
authors.affiliation: Department of Materials and Life Science, Seikei University, 3-3-1 Kichijoji-kitamachi, Musashino, Tokyo, 180-8633, Japan.
authors.forename: Taiki
authors.initials: T
authors.lastname: Kuribara
authors.affiliation: Department of Materials and Life Science, Seikei University, 3-3-1 Kichijoji-kitamachi, Musashino, Tokyo, 180-8633, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Hirano
authors.affiliation: School of Chemistry and Bio21 Molecular Science and, Biotechnology Institute, University of Melbourne, 30 Flemington Road, Parkville, VIC, 3010, Australia.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Speciale
authors.affiliation: School of Chemistry and Bio21 Molecular Science and, Biotechnology Institute, University of Melbourne, 30 Flemington Road, Parkville, VIC, 3010, Australia.
authors.forename: Spencer J
authors.initials: SJ
authors.lastname: Williams
authors.affiliation: Synthetic Cellular Chemistry Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
authors.forename: Yukishige
authors.initials: Y
authors.lastname: Ito
authors.affiliation: Department of Materials and Life Science, Seikei University, 3-3-1 Kichijoji-kitamachi, Musashino, Tokyo, 180-8633, Japan.
authors.forename: Kiichiro
authors.initials: K
authors.lastname: Totani
mesh_terms: D000818:Animals; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D004791:Enzyme Inhibitors; D006023:Glycoproteins / Q000378:metabolism*; D006801:Humans; D008358:Mannose / Q000378:metabolism; D008361:Mannosidases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051379:Mice; D021381:Protein Transport
chemical_list: D004791:Enzyme Inhibitors; D006023:Glycoproteins; D008361:Mannosidases; D008358:Mannose
keywords: enzymes; glycoproteins; inhibitors; protein folding; protein transport