title: Proteomics reveals N-linked glycoprotein diversity in Caenorhabditis elegans and suggests an atypical translocation mechanism for integral membrane proteins.
abstract: Protein glycosylation is one of the most common post-translational modifications in eukaryotes and affects various aspects of protein structure and function. To facilitate studies of protein glycosylation, we paired glycosylation site-specific stable isotope tagging of lectin affinity-captured N-linked glycopeptides with mass spectrometry and determined 1,465 N-glycosylated sites on 829 proteins expressed in Caenorhabditis elegans. The analysis shows the diversity of protein glycosylation in eukaryotes in terms of glycosylation sites and oligosaccharide structures attached to polypeptide chains and suggests the substrate specificity of oligosaccharyltransferase, a single multienzyme complex in C. elegans that incorporates an oligosaccharide moiety en bloc to newly synthesized polypeptides. In addition, topological analysis of 257 N-glycosylated proteins containing a putative single transmembrane segment that were identified based on the relative positions of glycosylation sites and transmembrane segments suggests that an atypical non-cotranslational mechanism translocates large N-terminal segments from the cytosol to the endoplasmic reticulum lumen in the absence of signal sequence function.
authors.affiliation: Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji, Tokyo 192-0397, Japan. kaji-rcmg@aist.go.jp
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kaji
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Kamiie
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Kawakami
authors.forename: Kazuki
authors.initials: K
authors.lastname: Kido
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Yamauchi
authors.forename: Takashi
authors.initials: T
authors.lastname: Shinkawa
authors.forename: Masato
authors.initials: M
authors.lastname: Taoka
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Takahashi
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Isobe
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000378:metabolism*; D006031:Glycosylation; D008562:Membrane Glycoproteins / Q000378:metabolism*; D021381:Protein Transport; D040901:Proteomics
chemical_list: D008562:Membrane Glycoproteins