Studies on the glycoproteins expressing neural specific carbohydrate

随着免疫技术和组织化学方法的进步，神经元特异性碳水化合物已被发现。这些携带神经特异性碳水化合物的糖缀合物主要存在于细胞表面，并在神经系统发育过程中以区域或阶段特异性的方式表达。因此，这些神经元特异性碳水化合物可能在神经细胞的识别和/或迁移中起重要作用。抗辣根过氧化物酶（HRP）的抗血清特异性标记蚱蜢和其他昆虫的神经系统，并已被证明识别在神经元表面表达的碳水化合物部分。为了确定糖表位的结构，我们用凝集素色谱法从蚱蜢神经系统中分离出表达神经元特异性糖抗原的糖蛋白。在还原条件下，SDS-PAGE显示糖蛋白表观分子量为35 kDa。通过α -甘露糖苷酶消化去除α -连接甘露糖残基，完全破坏了35 kDa糖蛋白与抗hrp抗体的结合活性。35 kDa糖蛋白的碳水化合物组成分析使用高效液相色谱系统与脉冲安培检测器。35 kDa的糖蛋白由Fuc、Man、Gal、Glc、GalNH2和GlcNH2组成，分子比分别为1.0、1.4、0.4、1.5、0.4和1.5。

With progress in immunological techniques and histochemical methods, neuron-specific carbohydrate moieties have been discovered. These glycoconjugates carrying the neural specific carbohydrates are mainly observed on the cell surface and expressed in region- or stage-specific manner during the development of the nervous system. Therefore, these neuron- specific carbohydrate moieties may play important roles in recognition and/or migration of neural cells. Antiserum raised against horseradish peroxidase(HRP)specifically labels the nervous system of grasshopper and other insects and has been shown to recognize carbohydrate moiety that is expressed on the surface of neurons.In order to determine the structure of the carbohydrate epitope, we isolated the glycoprotein which express the neuron- specific carbohydrate antigen, from grasshopper nervous system using lectin chromatography. The glycoprotein showed apparent molecular weight of 35 kDa on SDS-PAGE under reducing condition. Removal of alpha-linked mannose residues by digestion with alpha-mannosidase completely destroyed the binding activity of the 35 kDa glycoprotein to the anti-HRP antibody. The carbohydrate composition of the 35 kDa glycoprotein was analyzed using a HPLC system with a pulsed amperometry detector. The 35 kDa glycoprotein was composed of Fuc, Man, Gal, Glc, GalNH2, and GlcNH2 with a molecular ratio of 1.0,1.4, 0.4, 1.5, 0.4, and 1.5, respectively.