OST2/YOR103C Summary Help

Standard Name OST2 1
Systematic Name YOR103C
Feature Type ORF, Verified
Description Epsilon subunit of the oligosaccharyltransferase complex; located in the ER lumen; catalyzes asparagine-linked glycosylation of newly synthesized proteins (1, 2 and see Summary Paragraph)
Name Description OligoSaccharylTransferase 1
Chromosomal Location
ChrXV:516841 to 516449 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Gene Ontology Annotations All OST2 GO evidence and references
  View Computational GO annotations for OST2
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 5 genes
Classical genetics
Large-scale survey
reduction of function
133 total interaction(s) for 110 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 1
  • Affinity Capture-RNA: 2
  • Affinity Capture-Western: 15
  • Co-purification: 3
  • PCA: 15

Genetic Interactions
  • Dosage Rescue: 1
  • Negative Genetic: 81
  • Positive Genetic: 12
  • Synthetic Growth Defect: 2
  • Synthetic Lethality: 1

Expression Summary
Length (a.a.) 130
Molecular Weight (Da) 14,697
Isoelectric Point (pI) 9.89
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXV:516841 to 516449 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Last Update Coordinates: 2011-02-03 | Sequence: 2003-09-22
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..393 516841..516449 2011-02-03 2003-09-22
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | E.C. | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000005629

During N-linked glycosylation of proteins, oligosaccharide chains are assembled on the carrier molecule dolichyl pyrophosphate in the following order: 2 molecules of N-acetylglucosamine (GlcNAc), 9 molecules of mannose, and 3 molecules of glucose. These 14-residue oligosaccharide cores are then transferred to asparagine residues on nascent polypeptide chains in the endoplasmic reticulum (ER). As proteins progress through the Golgi apparatus, the oligosaccharide cores are modified by trimming and extension to generate a diverse array of glycosylated proteins (reviewed in 3, 4).

The oligosaccharyl transferase complex (OST complex) (EC transfers 14-sugar branched oligosaccharides from dolichyl pyrophosphate to asparagine residues. The complex contains nine protein subunits: Ost1p, Ost2p, Ost3p, Ost4p, Ost5p, Ost6p, Stt3p, Swp1p, and Wbp1p, all of which are integral membrane proteins of the ER. The OST complex interacts with the Sec61p pore complex (5) involved in protein import into the ER.

Ost2p is the epsilon subunit of the OST complex, one of the original six subunits purified (1, 6). OST2 is essential (1), but temperature-sensitive (ts) mutants are defective in core oligosaccharide transfer to proteins (1); O-linked glycosylation is unaffected (1). Some ts mutants form clumps in liquid culture at the permissive temperature, possibly due to defective separation of mother and daughter cells (1).

Ost2p is homologous to the vertebrate (not yeast) DAD1 (defender against apoptotic cell death) protein (OMIM) (1), a putative fourth component of the mammalian OST complex (7, 8).

Last updated: 2005-06-27 Contact SGD

References cited on this page View Complete Literature Guide for OST2
1) Silberstein S, et al.  (1995) The essential OST2 gene encodes the 16-kD subunit of the yeast oligosaccharyltransferase, a highly conserved protein expressed in diverse eukaryotic organisms. J Cell Biol 131(2):371-83
2) Knauer R and Lehle L  (1999) The oligosaccharyltransferase complex from yeast. Biochim Biophys Acta 1426(2):259-73
3) Herscovics A and Orlean P  (1993) Glycoprotein biosynthesis in yeast. FASEB J 7(6):540-50
4) Burda P and Aebi M  (1999) The dolichol pathway of N-linked glycosylation. Biochim Biophys Acta 1426(2):239-57
5) Chavan MM, et al.  (2005) Subunits of the translocon interact with components of the oligosaccharyl transferase complex. J Biol Chem 280(24):22917-24
6) Kelleher DJ and Gilmore R  (1994) The Saccharomyces cerevisiae oligosaccharyltransferase is a protein complex composed of Wbp1p, Swp1p, and four additional polypeptides. J Biol Chem 269(17):12908-17
7) Fu J, et al.  (1997) Interactions among subunits of the oligosaccharyltransferase complex. J Biol Chem 272(47):29687-92
8) Makishima T, et al.  (1997) The highly conserved DAD1 protein involved in apoptosis is required for N-linked glycosylation. Genes Cells 2(2):129-41