Disease relevance of DDOST

• A single high dose of 5 mg/kg (body weight) of monoclonal antibody SDZ OST 577 was intravenously administered to a chimpanzee, followed by intravenous challenge with 10(3.5) chimpanzee infectious doses of a wild-type HBV, the MS-2 strain (ayw subtype) [1].
• MSPMs included non-small-cell lung cancer (NSCLC) (four patients), hematologic malignancies (HM) (three patients), and 12 with other solid tumors (OST) [2].
• Two human osteosarcoma cell lines, Hu09 and OST, were suspended in Matrigel (Becton Dickinson Labware, Bedford, Massachusetts) and implanted subcutaneously in the backs of nude mice [3].
• With the use of human LDH as a marker, growth and remission of four human osteosarcomas (KOS-1, KOS-2, KOS-3, OST) and a malignant fibrous histiocytoma (KMF) transplanted into nude mice were monitored during chemotherapies (Adriamycin [doxorubicin], cisplatin, mitomycin C, cyclophosphamide and vincristine) [4].
• Bone formation was induced by diffusion chamber in an osteosarcoma cell line OST and a gastric adenocarcinoma cell line MKN45 [5].

High impact information on DDOST

• Oligosaccharyltransferase (OST) is an integral membrane protein that catalyzes N-linked glycosylation of nascent proteins in the lumen of the endoplasmic reticulum [6].
• We found that the eukaryotic primary consensus sequence for N-glycosylation is N terminally extended to D/E-Y-N-X-S/T (Y, X not equalP) for recognition by the bacterial oligosaccharyltransferase (OST) PglB [7].
• Here we use a GFP-tagged subunit of the OST complex (GFP-Dad1) that rescues the temperature-sensitive (ts) phenotype of tsBN7 cells, where Dad1 is degraded and N-glycosylation is inhibited, to study the lateral mobility of the TC by FRAP [8].
• Contrary to the OST complex from most eukaryotic cells, the Stt3p subunit of these parasites transfers in cell-free assays glycans with Man(7-9)GlcNAc(2) and Glc(1-3)Man(9)GlcNAc(2) compositions at the same rate [9].
• The oligosaccharyltransferase (OST) is a multimeric complex containing eight different proteins, one of which (Stt3p) is the catalytic subunit [9].

Chemical compound and disease context of DDOST

• In the present study, treatment with TNFalpha enhanced the invasiveness of two human osteosarcoma cell lines, OST and MNNG [10].
• A cisplatin (CDDP)-resistant human osteosarcoma cell line (OST/R) was established by continuous exposure to CDDP [11].

Biological context of DDOST

• This DDOST subunit gene is localized on chromosome 1p36.1 by fluorescence in situ hybridization analysis [12].
• Genome organization of human 48-kDa oligosaccharyltransferase (DDOST) [12].
• Oligosaccharyltransferase (OST) catalyzes the cotranslational transfer of high-mannose sugars to nascent polypeptides during N-linked glycosylation in the rough endoplasmic reticulum lumen [13].
• Here we show that the human DDOST 48-kDa subunit gene (HGMW-approved symbol DDOST) is organized into 11 exons expanding about 9 kb [12].
• Yeast molecular genetic methods have been instrumental in the functional characterization of the OST subunits, and have proven to be powerful tools for the identification of novel gene products that influence oligosaccharide transfer in vivo [14].

Anatomical context of DDOST

• Using two-dimensional Blue Native polyacrylamide gel electrophoresis/sodium dodecyl sulfate-polyacrylamide gel electrophoresis and mass spectrometry, we now demonstrate that mammalian OST can be isolated from solubilized, actively engaged ribosomes as multiple distinct protein complexes that range in size from approximately 500 to 700 kDa [13].
• The demonstration that DAD1 is a subunit of the OST suggests that induction of a cell death pathway upon loss of DAD1 in the tsBN7 cell line reflects the essential nature of N-linked glycosylation in eukaryotes [15].
• Immune IgG raised to recombinant OST-48 and 80K-H inhibited binding of AGE-bovine serum albumin to cell membranes in a dose-dependent manner [16].
• DAD1 can be crosslinked to OST48 in intact microsomes with dithiobis(succinimidylpropionate) [15].
• Immunostaining and flow cytometry demonstrated the surface expression of OST-48 and 80K-H on numerous cell types and tissues, including mononuclear, endothelial, renal, and brain neuronal and glial cells [16].

Associations of DDOST with chemical compounds

• We isolated mouse and human DDOST cDNAs from retinoic acid-treated mouse P19 EC cells and human NT-2 cells, respectively [12].
• The initial stage in the biosynthesis of N-linked glycoproteins, catalyzed by the enzyme oligosaccharyltransferase (OST), involves the transfer of a preassembled high-mannose oligosaccharide from a dolichol-linked oligosaccharide donor onto asparagine acceptor sites in nascent proteins in the lumen of the rough endoplasmic reticulum [14].
• The oligosaccharyltransferase (OST), which has its active site exposed on the luminal face of the endoplasmic reticulum (ER), catalyzes the transfer of preassembled high mannose oligosaccharides onto certain asparagine residues of nascent polypeptides [17].
• As may be expected, this defect in the OST complex at the non-permissive temperature caused also the underglycosylation of a secretory glycoprotein [17].
• We also show that the dilysine motif in OST48 functions as an ER localization motif because OST48 in which the two lysine residues are replaced by serine (OST48ss) is no longer retained in the ER and is found instead also at the plasma membrane [18].

Other interactions of DDOST

• In the case of the Tac chimera containing only the luminal domain of RII, which by itself exits from the ER and is rapidly degraded, it is retained in the ER and becomes stabilized when coexpressed with OST48 [18].

Analytical, diagnostic and therapeutic context of DDOST

• Western blot analysis of cell lysates showed that after 6 h at the non-permissive temperature, steady-state levels of the ribophorins were reduced by about 50%, and OST48 was barely detectable [17].
• Here, we demonstrate a direct interaction between Sss1p and a subunit of OST, Wbp1p, using the split-ubiquitin system and co-immunoprecipitation [19].
• Increases in OST protein were visualized by confocal microscopy at the plasma membrane [20].
• N-terminal sequence analysis identified the proteins as ribophorin I, ribophorin II (doublet), and a 50-kDa homologue of Wbp1, a yeast protein essential for N-glycosylation [21].
• This monoclonal antibody, OST 577, has been compared to hyperimmune gamma globulins in a Bureau of Biologics approved radioimmunoassay [22].

References