OST5/YGL226C-A Summary Help

Standard Name OST5 1
Systematic Name YGL226C-A
Feature Type ORF, Verified
Description Zeta subunit of the oligosaccharyltransferase complex of the ER lumen; complex catalyzes asparagine-linked glycosylation of newly synthesized proteins (1, 2 and see Summary Paragraph)
Name Description OligoSaccharylTransferase 1
Chromosomal Location
ChrVII:73158 to 72749 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Gene Ontology Annotations All OST5 GO evidence and references
  View Computational GO annotations for OST5
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 1 genes
Large-scale survey
157 total interaction(s) for 67 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 2
  • Affinity Capture-RNA: 3
  • Affinity Capture-Western: 9
  • Co-purification: 2
  • PCA: 4

Genetic Interactions
  • Dosage Rescue: 2
  • Negative Genetic: 71
  • Phenotypic Enhancement: 24
  • Phenotypic Suppression: 15
  • Positive Genetic: 15
  • Synthetic Growth Defect: 4
  • Synthetic Lethality: 6

Expression Summary
Length (a.a.) 86
Molecular Weight (Da) 9,517
Isoelectric Point (pI) 9.89
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrVII:73158 to 72749 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..21 73158..73138 2011-02-03 1996-07-31
Intron 22..170 73137..72989 2011-02-03 1996-07-31
CDS 171..410 72988..72749 2011-02-03 1996-07-31
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 SGDIDS000003194

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.

One of the original six OST complex subunits purified (6), Ost5p was eventually identified as the 9.5 kDa zeta subunit (1) in a synthetic lethal screen in alg5 mutant cells. Individually, deletions of either OST5 or ALG5 have only mild phenotypes, but deletion of both confers a synthetic temperature-sensitive (ts) glycosylation defect at 30° C (1).

Last updated: 2005-06-17 Contact SGD

References cited on this page View Complete Literature Guide for OST5
1) Reiss G, et al.  (1997) A specific screen for oligosaccharyltransferase mutations identifies the 9 kDa OST5 protein required for optimal activity in vivo and in vitro. EMBO J 16(6):1164-72
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