Names & Taxonomy

Uniprot ID:
Q8TCJ2
Entry Name:
STT3B_HUMAN
Status:
reviewed
Protein Names:
Dolichyl-diphosphooligosaccharide--protein glycosyltransferase subunit STT3B (Oligosaccharyl transferase subunit STT3B) (STT3-B) (EC 2.4.99.18) (Source of immunodominant MHC-associated peptides homolog)
Gene Names:
STT3B SIMP
Gene Names Primary:
STT3B
Organism:
Homo sapiens (Human)

Structure

Length:
826
Sequence:
MAEPSAPESKHKSSLNSSPWSGLMALGNSRHGHHGPGAQCAHKAAGGAAPPKPAPAGLSGGLSQPAGWQSLLSFTILFLAWLAGFSSRLFAVIRFESIIHEFDPWFNYRSTHHLASHGFYEFLNWFDERAWYPLGRIVGGTVYPGLMITAGLIHWILNTLNITVHIRDVCVFLAPTFSGLTSISTFLLTRELWNQGAGLLAACFIAIVPGYISRSVAGSFDNEGIAIFALQFTYYLWVKSVKTGSVFWTMCCCLSYFYMVSAWGGYVFIINLIPLHVFVLLLMQRYSKRVYIAYSTFYIVGLILSMQIPFVGFQPIRTSEHMAAAGVFALLQAYAFLQYLRDRLTKQEFQTLFFLGVSLAAGAVFLSVIYLTYTGYIAPWSGRFYSLWDTGYAKIHIPIIASVSEHQPTTWVSFFFDLHILVCTFPAGLWFCIKNINDERVFVALYAISAVYFAGVMVRLMLTLTPVVCMLSAIAFSNVFEHYLGDDMKRENPPVEDSSDEDDKRNQGNLYDKAGKVRKHATEQEKTEEGLGPNIKSIVTMLMLMLLMMFAVHCTWVTSNAYSSPSVVLASYNHDGTRNILDDFREAYFWLRQNTDEHARVMSWWDYGYQIAGMANRTTLVDNNTWNNSHIALVGKAMSSNETAAYKIMRTLDVDYVLVIFGGVIGYSGDDINKFLWMVRIAEGEHPKDIRESDYFTPQGEFRVDKAGSPTLLNCLMYKMSYYRFGEMQLDFRTPPGFDRTRNAEIGNKDIKFKHLEEAFTSEHWLVRIYKVKAPDNRETLDHKPRVTNIFPKQKYLSKKTTKRKRGYIKNKLVFKKGKKISKKTV
Proteomes:
UP000005640

Subcellular location

Subcellular Location:
Endoplasmic reticulum membrane; Multi-pass membrane protein.

Function

Function:
Catalytic subunit of the N-oligosaccharyl transferase (OST) complex which catalyzes the transfer of a high mannose oligosaccharide from a lipid-linked oligosaccharide donor to an asparagine residue within an Asn-X-Ser/Thr consensus motif in nascent polypeptide chains. 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). 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 cotranslational 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.
Pathway:
Protein modification; protein glycosylation.
Catalytic Activity:
Dolichyl diphosphooligosaccharide + -L-asparagine = dolichyl diphosphate + a glycoprotein with the oligosaccharide chain attached by N-beta-D-glycosyl linkage to a protein L-asparagine.
Gene Ontology Go:
endoplasmic reticulum
integral component of membrane
membrane
oligosaccharyltransferase complex
dolichyl-diphosphooligosaccharide-protein glycotransferase activity
co-translational protein modification
ER-associated ubiquitin-dependent protein catabolic process
glycoprotein catabolic process
post-translational protein modification
protein N-linked glycosylation via asparagine
response to unfolded protein
Gene Ontology Biological Process:
co-translational protein modification
ER-associated ubiquitin-dependent protein catabolic process
glycoprotein catabolic process
post-translational protein modification
protein N-linked glycosylation via asparagine
response to unfolded protein
Gene Ontology Molecular Function:
dolichyl-diphosphooligosaccharide-protein glycotransferase activity
Gene Ontology Cellular Component:
endoplasmic reticulum
integral component of membrane
membrane
oligosaccharyltransferase complex
Keywords:
Acetylation
Complete proteome
Congenital disorder of glycosylation
Endoplasmic reticulum
Glycoprotein
Glycosyltransferase
Membrane
Phosphoprotein
Reference proteome
Transferase
Transmembrane
Transmembrane helix

Publication

PubMed ID:
12439619 16641997 14702039 15489334 12887896 15835887 17081983 18669648 19413330 19167329 19159218 19690332 20068231 21269460 21406692 22607976 23842455 25944712