OST4/YDL232W Summary Help

Standard Name OST4 1
Systematic Name YDL232W
Feature Type ORF, Verified
Description Subunit of the oligosaccharyltransferase complex of the ER lumen; complex catalyzes protein asparagine-linked glycosylation; type I membrane protein required for incorporation of Ost3p or Ost6p into the OST complex (1, 2, 3, 4 and see Summary Paragraph)
Name Description OligoSaccharylTransferase 1
Chromosomal Location
ChrIV:38487 to 38597 | ORF Map | GBrowse
Gbrowse
Gene Ontology Annotations All OST4 GO evidence and references
  View Computational GO annotations for OST4
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 5 genes
Resources
Classical genetics
null
Large-scale survey
null
overexpression
Resources
80 total interaction(s) for 45 unique genes/features.
Physical Interactions
  • Affinity Capture-RNA: 3
  • Affinity Capture-Western: 30
  • Co-purification: 2
  • PCA: 22

Genetic Interactions
  • Dosage Rescue: 4
  • Negative Genetic: 1
  • Positive Genetic: 2
  • Synthetic Growth Defect: 7
  • Synthetic Lethality: 8
  • Synthetic Rescue: 1

Resources
Expression Summary
histogram
Resources
Length (a.a.) 36
Molecular Weight (Da) 3,985
Isoelectric Point (pI) 4.41
Localization
Phosphorylation PhosphoGRID | PhosphoPep Database
Structure
Homologs
sequence information
ChrIV:38487 to 38597 | ORF Map | GBrowse
SGD ORF map
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Relative
Coordinates
Chromosomal
Coordinates
Most Recent Updates
Coordinates Sequence
CDS 1..111 38487..38597 2011-02-03 1996-07-31
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
Resources
External Links All Associated Seq | E.C. | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000002391
SUMMARY PARAGRAPH for OST4

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 5, 6).

The oligosaccharyl transferase complex (OST complex) (EC 2.4.1.119) 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 (7) involved in protein import into the ER.

Ost4p and Stt3p were co-purified as the seventh and eighth components of the OST complex (8). Originally isolated as a vanadate-resistant mutant defective in oligosaccharyltransferase activity, OST4 encodes a protein of only 36 amino acids (1). Deletion of OST4 greatly reduces, but does not abolish, oligosaccharyltransferase activity, is lethal at 37° C, and causes cells to grow slowly at 25° C (1).

Last updated: 2005-06-17 Contact SGD

References cited on this page View Complete Literature Guide for OST4
1) Chi JH, et al.  (1996) The OST4 gene of Saccharomyces cerevisiae encodes an unusually small protein required for normal levels of oligosaccharyltransferase activity. J Biol Chem 271(6):3132-40
2) Knauer R and Lehle L  (1999) The oligosaccharyltransferase complex from yeast. Biochim Biophys Acta 1426(2):259-73
3) Kim H, et al.  (2003) Determination of the membrane topology of Ost4p and its subunit interactions in the oligosaccharyltransferase complex in Saccharomyces cerevisiae. Proc Natl Acad Sci U S A 100(13):7460-4
4) Spirig U, et al.  (2005) The 3.4-kDa Ost4 protein is required for the assembly of two distinct oligosaccharyltransferase complexes in yeast. Glycobiology 15(12):1396-406
5) Herscovics A and Orlean P  (1993) Glycoprotein biosynthesis in yeast. FASEB J 7(6):540-50
6) Burda P and Aebi M  (1999) The dolichol pathway of N-linked glycosylation. Biochim Biophys Acta 1426(2):239-57
7) Chavan MM, et al.  (2005) Subunits of the translocon interact with components of the oligosaccharyl transferase complex. J Biol Chem 280(24):22917-24
8) Karaoglu D, et al.  (1997) The highly conserved Stt3 protein is a subunit of the yeast oligosaccharyltransferase and forms a subcomplex with Ost3p and Ost4p. J Biol Chem 272(51):32513-20