LMPD Database

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LMP006028

UniProt Annotations

Entry Information
Gene NameSTT3B, subunit of the oligosaccharyltransferase complex (catalytic)
Protein EntrySTT3B_HUMAN
UniProt IDQ8TCJ2
SpeciesHuman
Comments
Comment typeDescription
Catalytic ActivityDolichyl diphosphooligosaccharide + [protein]- L-asparagine = dolichyl diphosphate + a glycoprotein with the oligosaccharide chain attached by N-beta-D-glycosyl linkage to a protein L-asparagine.
DiseaseCongenital disorder of glycosylation 1X (CDG1X) [MIM
FunctionCatalytic 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.
PathwayProtein modification; protein glycosylation.
Sequence CautionSequence=AAH15880.1; Type=Erroneous initiation; Note=Translation N-terminally extended.; Evidence= ; Sequence=BAB55370.1; Type=Erroneous initiation; Note=Translation N-terminally extended.; Evidence= ; Sequence=BAC11581.1; Type=Erroneous initiation; Note=Translation N-terminally extended.; Evidence= ;
SimilarityBelongs to the STT3 family.
Subcellular LocationEndoplasmic reticulum membrane; Multi-pass membrane protein.
SubunitComponent of the oligosaccharyltransferase (OST) complex (By similarity). OST seems to exist in different forms which contain at least RPN1, RPN2, OST48, DAD1, OSTC, KRTCAP2 and either STT3A or STT3B. OST can form stable complexes with the Sec61 complex or with both the Sec61 and TRAP complexes. {ECO
Tissue SpecificityExpressed in heart, brain, placenta, lung, liver, muscle, kidney and pancreas. Expressed in skin fibroblasts (at protein level).