Structure and Function of Non-Conventional Caveolins

Caveolins是一个不寻常的膜蛋白家族，作为心血管系统的关键调节因子发挥作用。 系统和新陈代谢。它们的主要生物学活动之一是塑造质膜以形成 瓶状内陷称为小窝。小窝蛋白和小窝的缺陷具有显著的生理学意义， 结果并破坏细胞内运输、信号传导、脂质稳态、机械传感和血浆 细胞膜的完整性。小窝蛋白和小窝是如何调节这么多不同的细胞 近30年来，功能一直是个谜，部分原因是缺乏有关结构的信息。 caveolins。令人兴奋的是，现状最近发生了变化。利用低温电子显微镜，我们现在 确定了负责小窝的小窝蛋白家族成员的第一个高分辨率结构 肌外生物发生，Caveolin-1（CAV 1）。由11个紧密排列的原聚体组成 盘，该结构代表蛋白质的低聚状态，其作为蛋白质的基本构建块。 小窝因此，现在有可能开始在机械水平上解决窖的形成和功能。 在这里，我们建议在确定CAV 1结构的基础上， 这个领域的难题无论是作为疾病相关突变的结果，还是作为 在自然选择中，一些小窝蛋白不能自己产生小窝。值得注意的是，这些“非- 传统的”小窝“仍然可以对小窝的组装和动力学产生深远的影响， 不同的生物功能。这是怎么发生的？为了深入了解这个长期存在的问题，我们 建议将CAV 1的性质与caveolin-2（CAV 2）进行比较和对比， 天然存在的小窝蛋白的实例，其只能在存在CAV 1的情况下形成小窝， 肺的正常生理功能。利用结构，生物化学，生物物理， 计算和细胞生物学测定，我们将1）确定CAV 2的独特结构特征如何 决定其与自身，CAV 1和其他蛋白质的相互作用，2）研究小窝蛋白使用的机制 复合物与膜结合并使膜弯曲并介导质膜稳态。这些 研究将提供关键的见解，了解窖蛋白如何与自己和彼此相互作用，以形成 以及小窝蛋白家族成员的独特结构特征如何决定 它们通过控制相互作用的蛋白质和脂质的库来实现其生物学功能。走上更 在基础水平上，拟议的研究将测试有关蛋白质如何插入膜的新想法 以及这如何影响它们塑造膜形态、组成和功能的能力。

Caveolins are a family of unusual membrane proteins that function as key regulators of the cardiovascular system and metabolism. One of their major biological activities is to shape the plasma membrane to form flask-shaped invaginations called caveolae. Defects in caveolins and caveolae have dramatic physiological consequences and disrupt intracellular trafficking, signaling, lipid homeostasis, mechanosensing, and plasma membrane integrity at the cellular level. How caveolins and caveolae regulate so many different cellular functions has remained a mystery for nearly 30 years, in part due to the lack of information about the structure of caveolins. Excitingly, the status quo recently changed. Using cryo-electron microscopy, we have now determined the first high-resolution structure of the caveolin family member responsible for caveolae biogenesis outside of muscle, caveolin-1 (CAV1). Consisting of 11 tightly packed protomers arranged in a disc, the structure represents an oligomeric state of the protein that serves as the fundamental building block of caveolae. It is thus now possible to begin to address how caveolae form and function at a mechanistic level. Here, we propose to build on lessons learned from determining the structure of CAV1 to tackle another ongoing conundrum in the field. Either as a consequence of disease-associated mutations or as a result of natural selection, some caveolins are unable to generate caveolae on their own. Remarkably, these “non- conventional” caveolins can still have profound effects on caveolae assembly and dynamics and even exert distinct biological functions. How does this happen? To gain insight into this long-standing question, we propose to compare and contrast the properties of CAV1 with caveolin-2 (CAV2), an evolutionarily conserved, naturally occurring example of a caveolin that can only form caveolae in the presence of CAV1 and is required for normal physiological function of the lung. Using a combination of structural, biochemical, biophysical, computational, and cell biological assays, we will 1) determine how the unique structural features of CAV2 dictate its interactions with itself, CAV1, and other proteins and 2) study mechanisms used by caveolin complexes to associate with and bend membranes and mediate plasma membrane homeostasis. These studies will provide critical insights into how caveolins interact with themselves and one another to form the building blocks of caveolae as well as how the distinct structural features of caveolin family members dictate their biological functions by controlling their repertoire of interacting proteins and lipids. On a more fundamental level, the proposed investigations will test new ideas about how proteins insert into membranes and how this influences their ability to mold membrane morphology, composition, and function.