Disordered proteins have long been known to help mediate tolerance to different abiotic stresses including freezing, osmotic stress, high temperatures, and desiccation in a diverse set of organisms. Recently, three novel families of intrinsically disordered proteins were identified in tardigrades, microscopic animals capable of surviving a battery of environmental extremes. These three families include the Cytoplasmic-, Secreted-, and Mitochondrial- Abundant Heat Soluble (CAHS, SAHS, and MAHS) proteins, which are collectively termed Tardigrade Disordered Proteins (TDPs). At the level of sequence conservation TDPs are unique to tardigrades, and beyond their high degree of disorder the CAHS, SAHS, and MAHS families do not resemble one another. All three families are either highly expressed constitutively, or significantly enriched in response to desiccation. In vivo, ex vivo, and in vitro experiments indicate functional roles for members of each TDP family in mitigating cellular perturbations induced by various abiotic stresses. What is currently lacking is a comprehensive and holistic understanding of the fundamental mechanisms by which TDPs function, and the properties of TDPs that allow them to function via those mechanisms. A quantitative and systematic approach is needed to identify precisely what cellular damage TDPs work to prevent, what sequence features are important for these functions, and how those sequence features contribute to the underlying mechanisms of protection. Such an approach will inform us not only about these fascinating proteins, but will also provide insights into how the sequence of a disordered protein can dictate its functional, structural, and dynamic properties.

中文翻译：

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极端胁迫耐受性中缓步动物紊乱蛋白的生物学特性

长期以来，人们都知道无序蛋白质有助于调节对不同非生物胁迫的耐受性，包括冷冻、渗透胁迫、高温和多种生物体的干燥。最近，在缓步动物（能够在一系列极端环境中幸存下来的微型动物）中发现了三个新的内在无序蛋白质家族。这三个家族包括细胞质-、分泌-和线粒体-丰富的热溶性（CAHS、SAHS 和 MAHS）蛋白，它们统称为缓步动物无序蛋白 (TDP)。在序列保守性的水平上，TDPs 是缓步动物所独有的，除了它们的高度紊乱之外，CAHS、SAHS 和 MAHS 家族彼此并不相似。这三个家族要么是组成型高度表达，要么 或因干燥而显着富集。体内、离体和体外实验表明每个 TDP 家族成员在减轻由各种非生物胁迫诱导的细胞扰动方面的功能作用。目前缺乏的是对 TDP 发挥作用的基本机制以及允许它们通过这些机制发挥作用的 TDP 特性的全面和整体理解。需要一种定量和系统的方法来精确确定 TDP 可以预防哪些细胞损伤、哪些序列特征对这些功能很重要，以及这些序列特征如何有助于潜在的保护机制。这种方法不仅可以让我们了解这些迷人的蛋白质，