Biophysical characterization and analysis of the cellular function of the neuronal Calciumsensor proteins Caldendrin and Calneurons

脑中Ca 2+信号的转导在神经变性、突触可塑性和神经元发育等多种基本过程中起着关键作用[1，2]。这种广泛的不同Ca 2+触发现象反映在大量不同Ca 2+结合蛋白（CaBP）的存在上，其中许多属于EF-手超家族[2]。神经元钙传感器（NCS）蛋白是EFhand超家族的成员，在神经元信号转导中发挥着多种多样的作用。它们的结构与其共同祖先钙调素的结构非常相似，具有四个EF-手Ca 2+结合基序。尽管它们的相似性程度相对较高，但NCS蛋白被认为在神经元中具有高度专门化的功能。一般认为，相对于它们的靶相互作用的特异性是由受限的亚细胞定位、Ca 2+结合亲和力的差异或它们的EF-手结构的修饰（其可能为蛋白质相互作用提供独特的界面）引起的。在这个应用程序中，我们要分析的分子动力学和神经元钙结合蛋白Caldendrin和Calneurons的细胞功能。我们将证明这一假设，即Caldendrin是一种突触Ca 2+和Zn 2+传感器，可以迅速改变其突触结合伴侣PSD 95的构象，这是一种可能有助于突触短时程增强的机制。此外，我们还希望研究Calneurons靶向trans-Golgi网络的机制，以及调控trans-Golgi网络中刺激依赖的动力学到质膜运输的机制。

The transduction of Ca2+-signals in the brain plays a pivotal role in such diverse and fundamental processes as neurodegeneration, synaptic plasticity and neuronal development [1, 2], This broad range of different Ca2+-triggered phenomena is reflected by the existence of a multitude of different Ca2+-binding proteins (CaBPs) from which numerous belong to the EF-hand super-family [2]. Neuronal calcium sensor (NCS) proteins are members ofthe EFhand super-family that play multiple and divergent roles in neuronal signaling. They closely resemble the structure of their common ancestor Calmodulin with four EF-hand Ca2+-binding motifs. Despite their relatively high degree of similarity NCS proteins are thought to serve highly specialized functions in neurons. It is generally believed that the specificity with respect to their target interactions is brought about by either a restricted subcellular localization, differences in Ca2+-binding affinities or modifications of their EF-hand structure that might provide a unique interface for protein interactions. In this application we want to analyze the molecular dynamics and cellular function of the neuronal Ca2+-binding proteins Caldendrin and Calneurons. We will prove the hypothesis that Caldendrin is a synaptic Ca2+- and Zn2+ sensor that rapidly changes the conformation of its synaptic binding partner PSD95, a mechanism that could contribute to short-term potentiation at the synapse. In addition we want to investigate the mechanisms by which Calneurons are targeted to the trans-Golgi network and regulate stimulus-dependent dynamics in trans-Golgi network to plasma membrane trafficking.