Analyzing the Complexins of the photoreceptor ribbon synapses in mouse retina

复杂蛋白（Cplxs） 1和2是高亲和力的snare相互作用蛋白。它们调节突触囊泡与质膜融合反应的一个后期步骤，很可能是通过稳定SNARE复合体来维持突触囊泡处于释放状态。与Cplxs 1和2不同的是Cplxs 3和Cplxs 4。它们与Cplxs 1和2具有有限的同源性，具有用于膜相互作用的c端CAAX-box基序，并且主要在脊椎动物视网膜的带状突触中表达。通过对cplx3 /4双敲除小鼠的研究，我们发现cplx3和cplx4在光感受器带状突触的神经递质释放中具有多种功能：它们抑制强直释放和促进诱发释放，并且它们可能在适应依赖性调节带状束缚释放突触囊泡的可用性中发挥作用。然而，到目前为止，该领域最基本的问题尚未得到解决：视网膜Cplx功能的潜在分子和细胞生物学机制是什么？为了解决这个问题，我们将研究Cplxs 3和4的适应依赖性表达（RNA，蛋白质），以及它们在可溶性和不可溶性（膜相关）形式之间的转换，这可能取决于它们独特的C端的法尼化。此外，我们将寻找可能影响cplx3和4细胞生物学的相互作用伙伴，特别是它们的功能可用性（调节器），并可能调节下游Cplx功能，从而以活动依赖的方式释放递质（效应器）。

The Complexins (Cplxs) 1 and 2 are high affinity SNARE-interacting proteins. They regulate a late step in the synaptic vesicle fusion reaction with the plasma membrane, most likely by stabilizing the SNARE complex in order to maintain synaptic vesicles in a release competent state. Different from the Cplxs 1 and 2 are the Cplxs 3 and 4. They show limited homology to the Cplxs 1 and 2, possess a C-terminal CAAX-box motif for membrane interaction and are predominantly expressed at ribbon synapses of the vertebrate retina. From a previous study examining Cplx 3/4 double-knockout mice, we know that the Cplxs 3 and 4 have diverse functions in neurotransmitter release from photoreceptor ribbon synapses: they suppress tonic and facilitate evoked release, and they play a putative role in the adaptation-dependent regulation of the availability of ribbon-tethered releasable synaptic vesicles. However, the most fundamental question in the field has not been approached so far: what are the underlying molecular and cell biological mechanisms of retinal Cplx function? To address this question, we will study the adaptation-dependent expression (RNA, protein) of the Cplxs 3 and 4, and their switching between soluble and insoluble (membrane-associated) forms, which may depend on farnesylation of their unique C terminus. Moreover, we will search for interaction partners, which may influence the cell biology of the Cplxs 3 and 4 in general and their functional availability in particular (regulators), and which may modulate downstream Cplx functions and thereby transmitter release in an activity-dependent manner (effectors).