BIOGRID CURATED DATA FOR PUBLICATION: The highly conserved Stt3 protein is a subunit of the yeast oligosaccharyltransferase and forms a subcomplex with Ost3p and Ost4p.

Protein-Protein, Genetic, and Chemical Interactions for Karaoglu D (1997):The highly conserved Stt3 protein is a subunit of the yeast oligosaccharyltransferase and forms a subcomplex with Ost3p and Ost4p. curated by BioGRID (https://thebiogrid.org); ABSTRACT: The oligosaccharyltransferase has been purified from Saccharomyces cerevisiae as an hetero-oligomeric complex composed of four or six subunits. Here, the in vivo subunit composition and stoichiometry of the oligosaccharyltransferase were investigated by attaching an epitope coding sequence to a previously characterized subunit gene, OST3. Five (Ost1p, Wbp1p, Swp1p, Ost2p, and Ost5p) of the seven polypeptides that were coimmunoprecipitated with the epitope-tagged Ost3p were identical to those obtained by the conventional purification procedure. Two additional coprecipitating polypeptides with apparent molecular masses of 60 and 3.6 kDa were identified as the 78-kDa Stt3 protein and the 36-residue Ost4 protein, respectively. Stt3p and Ost4p were previously identified in screens for gene products involved in N-linked glycosylation. Quantification of the in vivo radiolabeled subunits and the radioiodinated purified enzyme shows that the yeast oligosaccharyltransferase is composed of equimolar amounts of eight subunits. Exposure of the immunoprecipitated oligosaccharyltransferase to mild protein denaturants yielded a subcomplex comprised of Stt3p, Ost3p, and Ost4p. These experiments, taken together with genetic and biochemical evidence for subunit interactions, suggest that the enzyme is composed of the following three subcomplexes: (a) Stt3p-Ost4p-Ost3p, (b) Swp1p-Wbp1p-Ost2p, and (c) Ost1p-Ost5p.

蛋白质-蛋白质、遗传和化学相互作用数据集，由 Karaoglu D (1997) 提出：高度保守的 Stt3 蛋白是酵母寡糖基转移酶的一个亚基，并与 Ost3p 和 Ost4p 构成亚复合体。该数据集由 BioGRID (https://thebiogrid.org) 精心编纂；摘要：寡糖基转移酶已被纯化自酿酒酵母，作为一个由四个或六个亚基组成的异源寡聚复合体。本研究通过将一个已知亚基基因 OST3 的表位编码序列进行标记，对寡糖基转移酶的体内亚基组成和化学计量进行了探究。在共免疫沉淀实验中，与标记的 Ost3p 共沉淀的七种多肽中的五种（Ost1p、Wbp1p、Swp1p、Ost2p 和 Ost5p）与通过传统纯化方法获得的相同。另外两种分子量分别为 60 和 3.6 kDa 的共沉淀多肽被鉴定为 78 kDa 的 Stt3 蛋白和 36 个氨基酸残基的 Ost4 蛋白。Stt3p 和 Ost4p 在先前关于参与 N-连接糖基化的基因产物的筛选中已被识别。体内放射性标记的亚基和放射性碘标记的纯化酶的定量分析表明，酵母寡糖基转移酶由等摩尔量的八个亚基组成。将免疫沉淀的寡糖基转移酶暴露于温和的蛋白质变性剂中，得到了由 Stt3p、Ost3p 和 Ost4p 组成的亚复合体。这些实验与亚基相互作用的遗传学和生化证据相结合，表明该酶由以下三个亚复合体构成：(a) Stt3p-Ost4p-Ost3p、(b) Swp1p-Wbp1p-Ost2p 和 (c) Ost1p-Ost5p。