Tbio STT3B Dolichyl-diphosphooligosaccharide--protein glycosyltransferase subunit STT3B

Protein Summary

Description

Catalytic subunit of the oligosaccharyl transferase (OST) complex that catalyzes the initial transfer of a defined glycan (Glc(3)Man(9)GlcNAc(2) in eukaryotes) from the lipid carrier dolichol-pyrophosphate to an asparagine residue within an Asn-X-Ser/Thr consensus motif in nascent polypeptide chains, the first step in protein N-glycosylation. N-glycosylation occurs cotranslationally and the complex associates with the Sec61 complex at the channel-forming translocon complex that mediates protein translocation across the endoplasmic reticulum (ER). All subunits are required for a maximal enzyme activity. This subunit contains the active site and the acceptor peptide and donor lipid-linked oligosaccharide (LLO) binding pockets (By similarity). STT3B is present in a small subset of OST complexes and mediates both cotranslational and post-translational N-glycosylation of target proteins: STT3B-containing complexes are required for efficient post-translational glycosylation and while they are less competent than STT3A-containing complexes for cotranslational glycosylation, they have the ability to mediate glycosylation of some nascent sites that are not accessible for STT3A. STT3B-containing complexes also act post-translationally and mediate modification of skipped glycosylation sites in unfolded proteins. Plays a role in ER-associated degradation (ERAD) pathway that mediates ubiquitin-dependent degradation of misfolded endoplasmic reticulum proteins by mediating N-glycosylation of unfolded proteins, which are then recognized by the ERAD pathway and targeted for degradation. Mediates glycosylation of the disease variant AMYL-TTR 'Asp-38' of TTR at 'Asn-118', leading to its degradation (PubMed:19167329, PubMed:22607976). The protein encoded by this gene is a catalytic subunit of a protein complex that transfers oligosaccharides onto asparagine residues. Defects in this gene are a cause of congenital disorder of glycosylation Ix (CDG1X). [provided by RefSeq, Jun 2014]

Uniprot Accession IDs

• Q8TCJ2
• Q96JZ4
• Q96KY7
• Oligosaccharyl transferase subunit STT3B

Gene Name

• STT3B

Ensembl ID

• ENST00000295770
• ENSP00000295770
• ENSG00000163527

Symbol

• SIMP
• SIMP
• CDG1X
• STT3-B

Knowledge Table

Most Knowledge About	Knowledge Value (0 to 1 scale)
transcription factor binding site profile	0.93
virus perturbation	0.88
small molecule perturbation	0.86
transcription factor perturbation	0.84
histone modification site profile	0.71

Protein Classes

PANTHER Classes

Protein / Transferase / Glycosyltransferase / Dolichyl-diphosphooligosaccharide--protein Glycosyltransferase Subunit Stt3b

DTO Classes

Protein / Enzyme / Transferase / Glycosyltransferase / Dolichyl-diphosphooligosaccharide--protein Glycosyltransferase Subunit Stt3b

IDG Development Level Summary

Tdark

These are targets about which virtually nothing is known. They do not have known drug or small molecule activities
- AND - satisfy two or more of the following criteria:

Pubmed score: 24.02   (req: < 5)

Gene RIFs: 13   (req: <= 3)

Antibodies: 36   (req: <= 50)

Tbio

These targets do not have known drug or small molecule activities
- AND - satisfy two or more of the following criteria:

Pubmed score: 24.02   (req: >= 5)

Gene RIFs: 13   (req: > 3)

Antibodies: 36   (req: > 50)

- OR - satisfy the following criterion:

Gene Ontology Terms: 8

Tchem

Target has at least one ChEMBL compound with an activity cutoff of < 30 nM - AND - satisfies the preceding conditions

Active Ligand: 0

Tclin

Target has at least one approved drug - AND - satisfies the preceding conditions

Active Drug: 0