EXTRACELLULAR MATRIX NERVE TERMINAL ANCHORAGE PROTEINS

没有突触前膜蛋白将神经末梢固定在 细胞外基质(ECM)是已知的。我提出的研究的目标是 鉴定和鉴定其中一些与锚定有关的蛋白质 神经末梢。这些蛋白质可以介导众所周知的营养性 神经末梢与基底板在神经过程中的相互作用 再生。因此，特别令人感兴趣的将是那些 是特定于突触亚群的。 我们已经从弹性肌电器官中鉴定出一种蛋白多糖 具有这种锚定蛋白的一些特征。它被找到了 在神经末梢表面，仅限于突触区域。它是 与细胞外基质(ECM)组分紧密结合并富含。 耐人寻味的是，这种蛋白多糖含有一种抗原决定簇 仅与电器官神经元有关。最后，突触 囊泡还含有一种跨膜蛋白多糖，这种蛋白多糖具有这种特性 抗原决定簇。因此，突触小泡也可能包含这一点 相同的蛋白多糖。 根据这些数据，我们假设这种蛋白多糖是突触前的 连接神经末梢和细胞外基质的膜蛋白。此外, 突触小泡可以作为运送这种分子的交通工具 从神经末梢表面。 本研究方案有两个基本目标：1)确定效度 2)识别和描述其他突触前 锚定突触细胞外基质的膜蛋白。 要实现第一个目标，需要几个步骤。我们将决定 蛋白多糖是否是由存在或存在的完整膜蛋白 没有疏水的尾巴。我们将确定以下ECM组件 结合蛋白多糖。如果蛋白多糖是一个完整的膜蛋白 并结合ECM成分，它必须将神经末梢与基质联系起来。 如果这种联系是通过途径特异的抗原决定簇进行的，这 这种联系可能是这个突触特有的。两种生物化学方法的比较 突触小泡和细胞外基质蛋白多糖蛋白核心将决定 这两个分子可能共享前体-产物关系。至 实现第二个目标我们将使用ECM分数，在其中神经 末端蛋白多糖最初是被发现的。我们将分离出一个亚组分 含有该ECM材料中所含的完整的膜蛋白。 如果突触前膜蛋白(蛋白多糖除外)与 ECM，它们应该出现在这个亚组分中。通过制作单克隆 针对这个亚组分的抗体，我们应该能够识别它们。

No presynaptic membrane proteins which anchor nerve terminals to the extracellular matrix (ECM) are known. The goal of my proposed research is to identify and characterize some of these proteins involved with anchoring nerve terminals. Such proteins could mediate the well-known trophic interactions between the nerve terminal and basal lamina during nerve regeneration. Of special interest, therefore, will be those proteins that are specific for a subgroup of synapses. We have identified a proteoglycan from elasmobranch electric organ which has some of the characteristics of such an anchoring protein. It is found on the nerve terminal surface restricted to the synaptic region. It is tightly bound to and enriched in an extracellular matrix (ECM) fraction. Intriguingly, this proteoglycan contains an antigenic determinant which is only associated with the electric organ neurons. Finally, synaptic vesicles also contain a transmembrane proteoglycan which shares this antigenic determinant. Thus, synaptic vesicles also might contain this same proteoglycan. From this data we hypothesize that this proteoglycan is presynaptic membrane protein which links the nerve terminal to the ECM. In addition, the synaptic vesicles may act as vehicles for shuttling this molecule to and from the nerve terminal surface. This research proposal has two basic goals: 1) to determine the validity of the above hypothesis; 2) to identify and characterize other presynaptic membrane proteins which anchor the synaptic ECM. To accomplish the first goal several steps are required. We will determine whether the proteoglycan is an integral membrane protein by the presence or absence of a hydrophobic tail. We will identify the ECM components which bind the proteoglycan. If the proteoglycan is an integral membrane protein and binds ECM components, it must link the nerve terminal to the matrix. If this linkage is through the pathway specific antigenic determinant, this linkage could be specific to this synapse. A biochemical comparison of the synaptic vesicle and ECM proteoglycan protein cores will determine whether these two molecules could share a precursor-product relationship. To achieve the second goal we will use the ECM fraction, in which the nerve terminal proteoglycan was originally found. We will isolate a subfraction containing the integral membrane proteins contained in this ECM material. If presynaptic membrane proteins (other than the proteoglycan) bind to the ECM, they should be present in this subfraction. By making monoclonal antibodies against this subfraction, we should be able to identify them.