OST3 dolichyl-diphosphooligosaccharide--protein glycotransferase OST3 [Saccharomyces cerevisiae S288C] - Gene

Summary

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Official Symbol: OST3
Official Full Name: dolichyl-diphosphooligosaccharide--protein glycotransferase OST3
Primary source: SGD:S000005611
Locus tag: YOR085W
See related: AllianceGenome:SGD:S000005611; FungiDB:YOR085W; VEuPathDB:YOR085W
Gene type: protein coding
RefSeq status: REVIEWED
Organism: Saccharomyces cerevisiae S288C (strain: S288C)
Lineage: Eukaryota; Fungi; Dikarya; Ascomycota; Saccharomycotina; Saccharomycetes; Saccharomycetales; Saccharomycetaceae; Saccharomyces
Summary: Enables dolichyl-diphosphooligosaccharide-protein glycotransferase activity and protein-disulfide reductase activity. Involved in protein N-linked glycosylation and protein O-linked mannosylation. Located in membrane. Part of oligosaccharyltransferase complex. Human ortholog(s) of this gene implicated in X-linked immunodeficiency with magnesium defect, Epstein-Barr virus infection, and neoplasia; autosomal recessive intellectual developmental disorder 7; and congenital disorder of glycosylation Icc. Orthologous to human MAGT1 (magnesium transporter 1) and TUSC3 (tumor suppressor candidate 3). [provided by Alliance of Genome Resources, Mar 2025]
Orthologs: all
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Genomic context

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See OST3 in Genome Data Viewer

Location:: chromosome: XV

Exon count:: 1

Sequence:: Chromosome: XV; NC_001147.6 (482033..483085)

Chromosome XV - NC_001147.6 Genomic Context describing neighboring genes

Genomic regions, transcripts, and products

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Go to reference sequence details

Genomic Sequence:: NC_001147.6

Go to nucleotide: Graphics FASTA GenBank

Bibliography

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GeneRIFs: Gene References Into Functions

What's a GeneRIF?

Substrate specificities and reaction kinetics of the yeast oligosaccharyltransferase isoforms.
Title: Substrate specificities and reaction kinetics of the yeast oligosaccharyltransferase isoforms.
Reductive stress in the endoplasmic reticulum (ER) inhibits the Ost3-dependent N-glycosylation of Sil1, which regulates specific BiP functions appropriate to the needs of the ER under reductive stress.
Title: Diminished Ost3-dependent N-glycosylation of the BiP nucleotide exchange factor Sil1 is an adaptive response to reductive ER stress.
OST3 and OST6 oligosaccharyltransferase subunits bind polypeptide substrate to locally enhance N-glycosylation.
Title: Oligosaccharyltransferase subunits bind polypeptide substrate to locally enhance N-glycosylation.
these assays showed that the thioredoxin-like active sites of Ost3p and Ost6p could form transient mixed disulfide bonds with cysteines in a model substrate glycoprotein, consistent with the function of Ost3p and Ost6p in modulating N-glycosylation substrate selection by OTase in vivo.
Title: Mixed disulfide formation in vitro between a glycoprotein substrate and yeast oligosaccharyltransferase subunits Ost3p and Ost6p.
Data support a model of Ost3/6p function in which they transiently bind stretches of nascent polypeptide substrate to inhibit protein folding, thereby increasing glycosylation efficiency at nearby asparagine residues.
Title: Polypeptide binding specificities of Saccharomyces cerevisiae oligosaccharyltransferase accessory proteins Ost3p and Ost6p.
Mutation of the active-site cysteine residues of Ost6p and its paralogue Ost3p affected the glycosylation efficiency of a subset of glycosylation sites.
Title: Oxidoreductase activity of oligosaccharyltransferase subunits Ost3p and Ost6p defines site-specific glycosylation efficiency.
The paralogues Ost3p and Ost6p were required for efficient glycosylation of distinct defined glycosylation sites.
Title: Analysis of glycosylation site occupancy reveals a role for Ost3p and Ost6p in site-specific N-glycosylation efficiency.
Ost4p is required for the incorporation of either Ost3p or Ost6p into the oligosaccharyltransferase complex
Title: The 3.4-kDa Ost4 protein is required for the assembly of two distinct oligosaccharyltransferase complexes in yeast.
OST consists of two isoforms with distinct functions differing only in the presence of the two related Ost3 and Ost6p proteins
Title: Yeast oligosaccharyltransferase consists of two functionally distinct sub-complexes, specified by either the Ost3p or Ost6p subunit.
Ost3p and Ost6p are similar, but do not exist in the same oligosaccharyltransferase complex: Ost3p interacts with Sbh1p, while Ost6p interacts with Sbh2p.
Title: Two oligosaccharyl transferase complexes exist in yeast and associate with two different translocons.

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Pathways from PubChem

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Interactions

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Products	Interactant	Other Gene	Complex	Source	Pubs	Description

General gene information

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Homology

NCBI Orthologs

Orthologs from OrthoDB

Gene Ontology Provided by SGD

Function	Evidence Code	Pubs
enables dolichyl-diphosphooligosaccharide-protein glycotransferase activity	IMP Inferred from Mutant Phenotype more info	PubMed
enables protein-disulfide reductase activity	IDA Inferred from Direct Assay more info	PubMed

Process	Evidence Code	Pubs
involved_in protein N-linked glycosylation	IGI Inferred from Genetic Interaction more info	PubMed
involved_in protein N-linked glycosylation	IMP Inferred from Mutant Phenotype more info	PubMed
involved_in protein N-linked glycosylation	IPI Inferred from Physical Interaction more info	PubMed
involved_in protein N-linked glycosylation via asparagine	IBA Inferred from Biological aspect of Ancestor more info
involved_in protein O-linked mannosylation	IGI Inferred from Genetic Interaction more info	PubMed
acts_upstream_of_or_within protein glycosylation	IEA Inferred from Electronic Annotation more info
involved_in protein glycosylation	IMP Inferred from Mutant Phenotype more info	PubMed

Component	Evidence Code	Pubs
located_in endoplasmic reticulum	HDA more info	PubMed
located_in endoplasmic reticulum	IEA Inferred from Electronic Annotation more info
located_in endoplasmic reticulum membrane	IEA Inferred from Electronic Annotation more info
located_in membrane	IEA Inferred from Electronic Annotation more info
located_in membrane	IMP Inferred from Mutant Phenotype more info	PubMed
part_of oligosaccharyltransferase complex	IBA Inferred from Biological aspect of Ancestor more info
part_of oligosaccharyltransferase complex	IDA Inferred from Direct Assay more info	PubMed
part_of oligosaccharyltransferase complex	IPI Inferred from Physical Interaction more info	PubMed

General protein information

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Preferred Names: dolichyl-diphosphooligosaccharide--protein glycotransferase OST3

NP_014728.1

Gamma subunit of the oligosaccharyltransferase complex of the ER lumen; complex catalyzes asparagine-linked glycosylation of newly synthesized proteins; Ost3p is important for N-glycosylation of a subset of proteins including modification of Pmt2p at N131 and N403

NCBI Reference Sequences (RefSeq)

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Genome Annotation

The following sections contain reference sequences that belong to a specific genome build. Explain

Reference assembly

Genomic

NC_001147.6 Reference assembly

Range

482033..483085

Download

GenBank, FASTA, Sequence Viewer (Graphics)

mRNA and Protein(s)

NM_001183504.1 → NP_014728.1 TPA: dolichyl-diphosphooligosaccharide--protein glycotransferase OST3 [Saccharomyces cerevisiae S288C]

See identical proteins and their annotated locations for NP_014728.1

Status: REVIEWED

UniProtKB/Swiss-Prot

D6W2E7, P48439

UniProtKB/TrEMBL

A6ZNT6, B3LJD3, B5VRY1, C7GT31, C8ZI47, N1NWX3

Conserved Domains (1) summary

pfam04756
Location:26 → 340

OST3_OST6; OST3 / OST6 family, transporter family