SORTING AND TRANSPORT OF SPECIFIC NEURONAL GLYCOPROTEINS

本建议中的工作涉及两个至关重要的问题， 我们对神经元功能和发育的理解。 一是 确定膜糖蛋白是如何在细胞体中合成的， 神经元被选择性地路由到突触前和突触后末端。 这些 这些过程对于表面膜的正确组装和 神经元质膜的不同区域是如何维持在一个 功能和结构上的差异状态。 第二种情况是 糖蛋白作为神经元间介导物的可能作用 识别和粘附。 我和我的同事打算探索这些 点使用一个单一的细胞- R2的巨大的神经元的Aaplasia californica。 R2的细胞体、突触前和突触后区域在解剖学上是 容易接近 此外，R2只合成10种膜糖蛋白， 相对于糖蛋白组分的复杂性， 从脊椎动物的神经组织中分离出来 R2的两种糖蛋白在细胞中具有明显不同的目的地。 细胞：糖蛋白-I是细胞表面的主要糖蛋白， 细胞索马，而糖蛋白-V优先输出到轴突 在那里它被迅速地输送到R2的突触。 的位点 将通过免疫细胞化学测定两种糖蛋白的分选 在超微结构水平上，使用针对每个 糖蛋白 此外，两者的寡糖链 糖蛋白的特征在于， 糖基部分是负责分选的信号。 R2、GCN和R15是三个大的已识别神经元，它们在神经元的功能上不同。 功能、位置和神经递质类型。 我们会研究 糖蛋白存在于细胞体表面和细胞末端， 这些神经元，以直接测试的假设，神经元可以 以它们的糖蛋白成分区分。 的许多特征 提出的实验是独特的，并提出了一个统一的，多学科的 这是一种对我们的神经元知识至关重要的问题的方法。

The work in this proposal addresses two issues of fundamental importance to our understanding of neuronal function and development. The first is to determine how membrane glycoproteins synthesized in the cell body of a neuron are selectively routed to the pre- and postsynaptic terminal. These processes are central to the proper assembly of surface membranes and to how distinct regions of the neuronal plasma membrane are maintained in a functionally and structurally differentiated state. The second concerns the possible role of glycoproteins as mediators of interneuronal recognition and adhesion. My colleagues and I intend to explore these points using a single cell - R2 the giant neuron of Aplysia californica. R2's cell body, presynaptic, and postsynaptic regions are anatomically accessible. Moreover, R2 synthesizes only ten membrane glycoproteins, a remarkable simplicity relative to the complexity of glycoprotein fractions from vertebrate nervous tissue. Two of R2's glycoproteins have distinctly different destinations in the cell: glycoprotein-I is the major glycoprotein on the cell surface of the cell soma whereas glycoprotein-V is preferentially exported into the axon where it is rapidly transported towards R2's synapses. The site at which the two glycoproteins are sorted will be determined by immunocytochemistry at the ultrastructural level using monoclonal antibodies raised to each glycoprotein. In addition, the oligosaccharide chains of both glycoproteins will be characterized with the idea that a modification of a glycosyl moiety is the signal responsible for the sorting. R2, GCN, and R15 are three large identified neurons that differ in function, location, and neurotransmitter type. We will examine the glycoproteins present on the surface of the cell body and terminals of these neurons in order to test directly the hypothesis that neurons can be distinguished by their glycoprotein constituents. Many features of the proposed experiments are unique and present a unified, multidisciplinary approach to issues of major importance to our knowledge of the neuron.