Chernoff E A, Maresh G A, Culp L A
J Cell Biol. 1983 Mar;96(3):661-8. doi: 10.1083/jcb.96.3.661.
A high molecular weight glycoconjugate has been isolated from neurite-producing neuronal tumor cells in culture and has been designated as I(0) based on its elution characteristics in gel filtration chromatography. This molecule cannot be found in a variety of nonneuronal cells. I(0) is found in the substratum-attached material or cell fraction of neurite-producing neuroblastoma cells, depending upon culture conditions. It is found in the substratum-bound fraction of B104 rat neuroblastoma cells during serum starvation and in the EGTA-detached cell fraction of B104 cells grown in chemically defined N2 medium. It occurs only in the cell fraction of the human neuroblastoma line Platt. Examination of behavioral variants of the B104 rat line further strengthens the association of I(0) with neurite production; the constitutive neurite-producing E(R)B9 variant contains I(0) while the non-neurite-producing E(R)A11 variant does not. I(0) is large, eluting in the void volume of sepharose-CL2B columns. Radioiodination of intact cells with lactoperoxidase shows I(0) to be a cell surface component. Metabolic radiolabeling studies show that it contains a high proportion of polysaccharide to protein, does not contain mannose, and is unsulfated. Alkaline borohydride reduction release two size classes of large polysaccharide chain. The alkaline reduction results, along with the mannose incorporation studies, show the presence of O-glycosidic linkages and few, if any, N-linkages. Resistance to nitrous acid deamination, insensitivity to glycosaminoglycan lyases, and the absence of sulfation, indicate that I(0) does not contain the glycosaminoglycans hyaluronic acid, chondroitin-, dermatan-, or heparin- sulfates. Affinity column chromatography reveals high binding affinity of I(0) to polyornithine and no binding to gelatin (collagen) or the glycosaminoglycans hyaluronate and heparin. These studies describe a unique high molecular weight glycoconjugate on the surface of neurite-producing neuroblastoma cell lines from two species.
一种高分子量糖缀合物已从培养的产生神经突的神经元肿瘤细胞中分离出来，并根据其在凝胶过滤色谱中的洗脱特性被命名为I(0)。在多种非神经元细胞中找不到这种分子。根据培养条件，I(0)存在于产生神经突的神经母细胞瘤细胞的附着于基质的物质或细胞组分中。在血清饥饿期间，它存在于B104大鼠神经母细胞瘤细胞的基质结合组分中，而在化学限定的N2培养基中生长的B104细胞的EGTA分离细胞组分中也能找到它。它仅存在于人类神经母细胞瘤系Platt的细胞组分中。对B104大鼠系行为变体的研究进一步加强了I(0)与神经突产生的关联；组成型产生神经突的E(R)B9变体含有I(0)，而非神经突产生的E(R)A11变体则没有。I(0)很大，在琼脂糖-CL2B柱的空体积中洗脱。用乳过氧化物酶对完整细胞进行放射性碘化显示I(0)是一种细胞表面成分。代谢放射性标记研究表明，它含有高比例的多糖与蛋白质，不含甘露糖，且未硫酸化。碱性硼氢化钠还原释放出两种大小类别的大多糖链。碱性还原结果以及甘露糖掺入研究表明存在O-糖苷键，且几乎没有N-键（如果有的话）。对亚硝酸脱氨的抗性、对糖胺聚糖裂解酶的不敏感性以及不存在硫酸化，表明I(0)不含有糖胺聚糖透明质酸、硫酸软骨素、硫酸皮肤素或硫酸肝素。亲和柱色谱显示I(0)对聚鸟氨酸具有高结合亲和力，对明胶（胶原蛋白）或糖胺聚糖透明质酸和肝素没有结合。这些研究描述了来自两个物种的产生神经突的神经母细胞瘤细胞系表面上一种独特高分子量糖缀合物。
