Structure and distribution of N-linked oligosaccharide chains on various domains of mouse tumour laminin.
Structure and distribution of N-linked oligosaccharide chains on various domains of mouse tumour laminin.
复制标题
小鼠肿瘤层粘连蛋白各个结构域上 N 连接寡糖链的结构和分布。
作者：
S. Fujiwara;H. Shinkai;R. Deutzmann;M. Paulsson;R. Timpl
通过肼水解从层粘连蛋白及其部分片段中分离出天冬酰胺连接的低聚糖，并经外糖苷酶消化纯化。这表明存在九种形式的复杂低聚糖链，它们在天线和低聚乳糖胺结构上不同，以及少量的高甘露糖型低聚糖。在末端半乳糖和唾液酸残基的取代方面发现了额外的变化。每一个不同的层粘连蛋白片段都显示出独特但不太复杂的碳水化合物结构。这些片段在质量、碳水化合物含量、层粘连蛋白分子内的定位以及细胞结合（片段1和6）、肝素和胶原结合（片段3和4）等功能活性方面也存在差异。碳水化合物含量特别高（72%）的片段7也显示出最高的三和四天线结构复杂性。这些片段之间的进一步差异用针对Gal α 1-3Gal表位的人抗体检测，该表位以高亲和力或低亲和力形式表达。拓扑结构不同的层粘连蛋白结构域的碳水化合物结构的差异可能对它们的功能和翻译后修饰事件的调节有影响。
Asparagine-linked oligosaccharides were liberated from laminin and some of its fragments by hydrazinolysis, and after purification characterized by exoglycosidase digestions. This demonstrated the presence of nine forms of complex oligosaccharide chains, which differed in antennary and oligolactosamine structure, and of small amounts of high-mannose-type oligosaccharides. Additional variations were found with regard to substitutions by terminal alpha-galactose and sialic acid residues. Each of the various laminin fragments showed a unique but less complex repertoire of carbohydrate structures. These fragments also differed in mass, carbohydrate content, localization within the laminin molecule and functional activities such as cell-binding (fragments 1 and 6) and heparin- and collagen-binding (fragments 3 and 4). Fragment 7 with a particularly high carbohydrate content (72%) also showed the highest complexity of tri- and tetra-antennary structures. Further differences between the fragments were detected with human antibodies against the Gal alpha 1-3Gal epitope, which was expressed in either a high-affinity or a low-affinity form. Such differences in carbohydrate structure of topologically distinct laminin domains may have implications for their functions and in the regulation of post-translational modification events.