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

脑内Ca2+信号的转导在神经退行性、突触可塑性和神经元发育等多种基础过程中起着关键作用[1,2]，Ca2+触发的多种不同现象反映在大量不同的Ca2+结合蛋白（cabp）的存在上，其中许多属于EF-hand超家族[2]。神经元钙传感器蛋白（NCS）是EFhand超家族的成员，在神经元信号传导中起着多种不同的作用。它们的结构与它们共同的祖先钙调蛋白非常相似，具有四个EF-hand Ca2+结合基序。尽管它们的相似性相对较高，但NCS蛋白被认为在神经元中具有高度特化的功能。一般认为，它们与靶相互作用的特异性是由受限的亚细胞定位、Ca2+结合亲和力的差异或EF-hand结构的修饰引起的，这些结构可能为蛋白质相互作用提供独特的界面。在这个应用中，我们想分析神经元Ca2+结合蛋白Caldendrin和calneuron的分子动力学和细胞功能。我们将证明Caldendrin是一种突触Ca2+-和Zn2+传感器，可以快速改变其突触结合伙伴PSD95的构象，这一机制可能有助于突触的短期增强。此外，我们希望研究calneuron靶向反式高尔基网络的机制，并调节反式高尔基网络中刺激依赖的动力学到质膜运输。

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.