Cages, Corrals and Vesicular Trafficking Shape the Diffusional Environment of the Plasma Membrane.

质膜是细胞内部与环境之间的屏障。这些膜通常被描述为自由漂浮的脂质的“海洋”，蛋白质“冰山”自由扩散（移动）通过“海洋”。实际上，膜被分成小区域，区域之间的移动受到膜嵌入结构的限制。这些扩散限制结构将膜分成承担专门功能的小区域，并且有多种类型的这些结构控制不同尺寸和时间尺度上的扩散。我们感兴趣的两个这些结构-correction和笼，更好地了解这些结构的组成和动力学的目标，并利用这些信息，开发一个模型的蛋白质扩散，占笼和correction的影响。围栏是由附着在细胞“骨架”上的“尖桩”蛋白质形成的“尖桩围栏”，并延伸穿过细胞膜以形成限制从围栏中流出的“渗透屏障”。我们最近的工作确定，皮质醇可以选择性地捕获旧蛋白，然后内吞（内化）将其从膜上去除。笼子--最近由我的NSERC研究项目发现--更神秘。它们的组成和作用尚不清楚，但它们在较短的时间内起着类似皮质激素的作用。我们已经初步确定了蛋白质血影蛋白作为笼的结构组成部分，并开发了直接成像笼和细胞膜中的细胞色素所需的工具。 在目标1中，我们将鉴定和表征形成笼的蛋白质。在目标2中，我们将讨论皮质醇是否选择性地从质膜上清除旧蛋白，以及新蛋白的释放（胞吐作用）是否清除皮质醇周围的膜。最后，我们将继续我们的蛋白质在细胞膜中扩散的数学模型的发展，因为目前的模型不考虑笼和coronary的作用。我们已经证明，连续时间随机游走模型最好地描述了一种蛋白质的扩散的corpendum和笼子的效果;在目标3中，我们将使用一组代表膜蛋白的主要结构类的蛋白质来确定该模型是否是蛋白质扩散的一般模型。 从长远来看，该计划将揭示用于组织细胞表面蛋白质的过程，并在短期内确定关键的结构机制及其组成。通过该计划培训的HQP获得了显微镜和计算机辅助分析方面的经验，以前的HQP利用这一专业知识开展职业生涯，开发下一代用于诊断MRI成像和组织学样本疾病的软件。该计划将继续我在显微镜和图像分析的高级形式的HQP成功培训，为这些学员提供显微镜和图像处理行业高度需求的技能。

The plasma membrane is the barrier between the inside of a cell and its environment. These membranes are often described as "seas" of free-floating lipids with protein "icebergs" that freely diffuse (move) through the "sea". In reality, membranes are divided into small regions, with movement between regions restricted by membrane-embedded structures. These diffusion-restricting structures divide membranes into small regions that take on specialized functions, and there are multiple types of these structures that control diffusion over different size and time scales. We are interested in two of these structures - corrals and cages, with the goal of better understanding the composition and dynamics of these structures, and using this information, develop a model of protein diffusion that accounts for the effects of cages and corrals. Corrals are "picket-fences" created by "picket" proteins that are attached to the cells "skeleton", and extend through the membrane to create a "percolation barrier" that limits egress from the corral. Our recent work determined that corrals may selectively trap old proteins, which are then endocytosed (internalized) to remove them from the membrane. Cages - recently discovered by my NSERC research program - are more mysterious. Their composition and role are unknown, but they act like corrals over shorter periods of time. We have tentatively identified the protein spectrin as a structural component of cages, and developed the tools needed to directly image cages and corrals in the cell membrane. In aim 1 we will identify and characterize the proteins which form cages. In aim 2 we will address whether corrals selectively remove older proteins from the plasma membrane, and whether the release (exocytosis) of new proteins clears the surrounding membrane of corrals. Lastly, we will continue our development of a mathematical model of protein diffusion in the cell membrane, as current models do not account for the role of cages and corrals. We have shown that the Continuous Time Random Walk model best describes the effect of corrals and cages on the diffusion of one protein; in aim 3 we will use a panel of proteins representing the major structure classes of membrane proteins to determine whether this model is a general model of protein diffusion. In the long-term this program will uncover the processes used to organize proteins on the cell surface, and in the short-term it will identify the key structuring mechanisms and their composition. The HQP trained by this program gain experience in microscopy and computer-aided analyses, with previous HQP using this expertise to launch careers developing the next generation of software for diagnosing diseases in MRI imaging and in histological samples. This program will continue my successful training of HQP in advanced forms of microscopy and image analysis, providing these trainees with skills which are highly in-demand in the microscopy and image processing industries.