Prions are proteins that can exist in several structurally and functionally distinct states, one or more of which is transmissible. Yeast proteins Sup35 and Rnq1 in prion state ([PSI⁺] and [PIN⁺], respectively) form oligomers and aggregates, which are transmitted from parents to offspring in a series of generations. Several pieces of indirect evidence indicate that these aggregates also possess amyloid properties, but their binding to amyloid-specific dyes has not been shown in vivo. Meanwhile, it is the specific binding to the Congo Red dye and birefringence in polarized light after such staining that is considered the gold standard for proving the amyloid properties of a protein. Here, we used immunoprecipitation to extract native fibrils of the Sup35 and Rnq1 proteins from yeast strains with different prion status. These fibrils are detected by electron microscopy, stained with Congo Red and exhibit yellow-green birefringence after such staining. All these data show that the Sup35 and Rnq1 proteins in prion state form amyloid fibrils in vivo. The technology of fibrils extraction in combination with standard cytological methods can be used to identify new pathological and functional amyloids in any organism and to analyze the structural features of native amyloid fibrils.

中文翻译：

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通过天然原纤维的免疫沉淀方法直接证明酵母朊病毒 [PSI+] 和 [PIN+] 的淀粉样蛋白性质

朊病毒是可以以几种结构和功能不同的状态存在的蛋白质，其中一种或多种是可传播的。朊病毒状态的酵母蛋白 Sup35 和 Rnq1（分别为 [ PSI ⁺ ] 和 [ PIN ⁺ ]）形成低聚物和聚集体，在一系列世代中从父母传给后代。一些间接证据表明这些聚集体也具有淀粉样蛋白特性，但它们与淀粉样蛋白特异性染料的结合尚未在体内显示. 同时，这种染色后与刚果红染料的特异性结合和偏振光的双折射被认为是证明蛋白质淀粉样蛋白特性的金标准。在这里，我们使用免疫沉淀从具有不同朊病毒状态的酵母菌株中提取 Sup35 和 Rnq1 蛋白的天然原纤维。这些原纤维通过电子显微镜检测，用刚果红染色，染色后呈现黄绿色双折射。所有这些数据表明，朊病毒状态的 Sup35 和 Rnq1 蛋白在体内形成淀粉样蛋白原纤维。原纤维提取技术与标准细胞学方法相结合，可用于鉴定任何生物体中新的病理性和功能性淀粉样蛋白，并分析天然淀粉样蛋白原纤维的结构特征。