Identification of synaptic alpha2delta binding partners

描述(申请人提供)：突触代表关键的转导机器，它将基于动作电位的信号转换为分泌的化学信息，然后再转换回突触后的电反应。这些过程的调节被认为是学习和记忆的关键机制的基础，突触通信功能障碍被怀疑是大脑功能的一些疾病状态的中心。众所周知，神经递质释放的关键触发因素是突触前终末电压门控钙通道的开放，进而导致钙离子的内流。钙离子进入和胞吐效率之间的高度非线性关系使钙通道功能和丰度的控制成为塑造突触力量的一个强有力的潜在杠杆点。我们最近证明，钙通道亚单位α2Delta的表达在决定海马神经元神经末梢存在多少钙通道时是限速的。我们的工作表明，它在两个不同的分子步骤中起作用：它作用于前向运输步骤，允许钙通道运输到突触；它在神经末梢局部作用，允许通道在突触前膜发挥作用。这第二步需要编码金属离子依赖的粘连位点的α2Delta内预测结构域的完整性。在许多其他蛋白质中，这个结构域赋予与细胞外伙伴的结合。我们预测，正确的alpha2Delta功能需要与突触表面尚未发现的结合伙伴相互作用。这项建议的目标是使用生化方法来确定这个结合伙伴(S)。

DESCRIPTION (provided by applicant): Synapses represent key transduction machines that convert action potential-based signals into secreted chemical messages which in turn are converted back into postsynaptic electrical responses. Modulation of these processes is thought to underlie critical mechanisms of learning and memory, and dysfunction of synaptic communication is suspected to be central in a number of diseased states of brain function. It has long been known that the critical trigger for neurotransmitter release is the opening of voltage-gated calcium channels within the presynaptic terminal which in turn leads to the influx of calcium. The highly-non-linear relationship between calcium entry and exocytosis efficiency places the control of calcium channel function and abundance as a potent potential leverage point in sculpting synaptic strength. We recently demonstrated that expression of a calcium channel subunit, alpha2delta, is rate-limiting in determining how many calcium channels are present at nerve terminals in hippocampal neurons. Our work showed that it acts at 2 distinct molecular steps: it acts in a forward trafficking step to allow calcium channels to traffic to synapses and it acts locally at nerve terminals to allow channels to function at the presynaptic membrane. This second step requires the integrity of a predicted domain within alpha2delta that encodes a metal-ion-dependent adhesion site. In many other proteins this domain confers binding to an extracellular partner. We predict that proper alpha2delta function requires interaction with an as-yet-discovered binding partner on the synaptic surface. The goal of this proposal is to use biochemical approaches to identify this(ese) binding partner(s).