Understanding the structure of PrP^Sc is without doubt a sine qua non to understand not only PrP^Sc propagation, but also critical features of that process such as the strain phenomenon and transmission barriers. While elucidation of the PrP^Sc structure has been full of difficulties, we now have a large amount of structural information that allows us to begin to understand it. This commentary article summarizes a round table that took place within the Prion 2018 meeting held in Santiago de Compostela to discuss the state of the art in this matter. Two alternative models of PrP^Sc exist: the PIRIBS and the 4-rung β-solenoid models. Both of them have relevant features. The 4-rung β-solenoid model agrees with experimental constraints of brain derived PrP^Sc obtained from cryo-EM and X-ray fiber diffraction studies. Furthermore, it allows facile accommodation of the bulky glycans that decorate brain-derived PrP^Sc. On the other hand, the infectious PrP23-144 amyloid exhibits a PIRIBS architecture. Perhaps, both types of structure co-exist.

毫无疑问，了解PrP ^Sc的结构不仅是了解PrP ^Sc的传播，而且是了解该过程的关键特征（如应变现象和传输障碍）的必要条件。尽管阐明PrP ^Sc结构充满了困难，但我们现在拥有大量的结构信息，可以让我们开始理解它。这篇评论文章总结了在圣地亚哥德孔波斯特拉举行的2018年Prion会议期间举行的一次圆桌会议，讨论了此事的最新状态。PrP ^Sc的两种替代模型存在：PIRIBS模型和4级β-螺线肌模型。两者都有相关的功能。4-梯级β-电磁体模型与从冷冻EM和X射线纤维衍射研究获得的脑源性PrP ^Sc的实验约束一致。此外，它可以轻松容纳装饰大脑衍生的PrP ^Sc的大聚糖。另一方面，传染性PrP23-144淀粉样蛋白表现出PIRIBS结构。也许，两种类型的结构并存。