Taxonomic group: fungi / Ascomycota
(Phylum: Ascomycota)
Organ / tissue: endoplasmic reticulum
The structure was elucidated in this paperNCBI PubMed ID: 21979948Publication DOI: 10.1074/jbc.M111.251371Journal NLM ID: 2985121RPublisher: Baltimore, MD: American Society for Biochemistry and Molecular Biology
Correspondence: stuart.moore
inserm.fr
Institutions: French National Institute of Health and Medical Research, Paris, France, Université Denis Diderot, Paris, France, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
In Saccharomyces cerevisiae, proteins with misfolded lumenal, membrane, and cytoplasmic domains are cleared from the endoplasmic reticulum (ER) by ER-associated degradation (ERAD)-L, -M, and -C, respectively. ERAD-L is N-glycan-dependent and is characterized by ER mannosidase (Mns1p) and ER mannosidase-like protein (Mnl1p), which generate Man(7)GlcNAc(2) (d1) N-glycans with non-reducing α1,6-mannosyl residues. Glycoproteins bearing this motif bind Yos9p and are dislocated into the cytoplasm and then deglycosylated by peptide N-glycanase (Png1p) to yield free oligosaccharides (fOS). Here, we examined yeast fOS metabolism as a function of cell growth in order to obtain quantitative and mechanistic insights into ERAD. We demonstrate that both Png1p-dependent generation of Man(7-10)GlcNAc(2) fOS and vacuolar α-mannosidase (Ams1p)-dependent fOS demannosylation to yield Man(1)GlcNAc(2) are strikingly up-regulated during post-diauxic growth which occurs when the culture medium is depleted of glucose. Gene deletions in the ams1Δ background revealed that, as anticipated, Mns1p and Mnl1p are required for efficient generation of the Man(7)GlcNAc(2) (d1) fOS, but for the first time, we demonstrate that small amounts of this fOS are generated in an Mnl1p-independent, Mns1p-dependent pathway and that a Man(8)GlcNAc(2) fOS that is known to bind Yos9p is generated in an Mnl1p-dependent, Mns1p-independent manner. This latter observation adds mechanistic insight into a recently described Mnl1p-dependent, Mns1p-independent ERAD pathway. Finally, we show that 50% of fOS generation is independent of ERAD-L, and because our data indicate that ERAD-M and ERAD-C contribute little to fOS levels, other important processes underlie fOS generation in S. cerevisiae.
glycoprotein, free oligosaccharides
Structure type: oligomer ; 1944 [M+NO3]-
Location inside paper: fig.7, table 2, M9b, M9(d1,d3,d4)
Aglycon: protein
Compound class: N-glycan, glucomannan
Contained glycoepitopes: IEDB_123886,IEDB_130701,IEDB_135813,IEDB_136104,IEDB_137340,IEDB_137485,IEDB_140116,IEDB_141793,IEDB_141807,IEDB_141828,IEDB_141829,IEDB_141830,IEDB_141831,IEDB_143632,IEDB_144983,IEDB_151079,IEDB_151531,IEDB_152206,IEDB_153212,IEDB_153220,IEDB_164174,IEDB_187201,IEDB_187238,IEDB_187239,IEDB_429156,IEDB_540671,IEDB_548907,IEDB_857734,IEDB_983930,SB_136,SB_191,SB_196,SB_197,SB_198,SB_33,SB_44,SB_53,SB_67,SB_72,SB_73,SB_74,SB_77,SB_85
Methods: MALDI-TOF MS, HPLC, enzymatic digestion, extraction, CC, ESI-QTOF-MS
Enzymes that release or process the structure: α1,2-mannosidase, β-mannosidase endo-β-N-acetylglucosaminidase, amyloglucosidase, α-mannosidase, protease
Related record ID(s): 43393, 43394, 43395, 43396, 43397, 43398
NCBI Taxonomy refs (TaxIDs): 4932Reference(s) to other database(s): GTC:G97455PT
Show glycosyltransferases
There is only one chemically distinct structure:
Found 
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