Tumova S, Woods A, Couchman J R
Department of Cell Biology and Cell Adhesion and the Matrix Research Center, University of Alabama, Birmingham, Alabama 35294, USA.
J Biol Chem. 2000 Mar 31;275(13):9410-7. doi: 10.1074/jbc.275.13.9410.
Numerous functions of heparan sulfate proteoglycans are mediated through interactions between their heparan sulfate glycosaminoglycan chains and extracellular ligands. Ligand binding specificity for some molecules, including many growth factors, is determined by complex heparan sulfate fine structure, where highly sulfated, iduronate-rich domains alternate with N-acetylated domains. Syndecan-4, a cell surface heparan sulfate proteoglycan, has a distinct role in cell adhesion, suggesting its chains may differ from those of other cell surface proteoglycans. To determine whether the specific role of syndecan-4 correlates with a distinct heparan sulfate structure, we have analyzed heparan sulfate chains from the different surface proteoglycans of a single fibroblast strain and compared their ability to bind the Hep II domain of fibronectin, a ligand known to promote focal adhesion formation through syndecan-4. Despite distinct molecular masses of glypican and syndecan glycosaminoglycans and minor differences in disaccharide composition and sulfation pattern, the overall proportion and distribution of sulfated regions and the affinity for the Hep II domain were similar. Therefore, adhesion regulation requires core protein determinants of syndecan-4.
硫酸乙酰肝素蛋白聚糖的许多功能是通过其硫酸乙酰肝素糖胺聚糖链与细胞外配体之间的相互作用介导的。包括许多生长因子在内的一些分子的配体结合特异性由复杂的硫酸乙酰肝素精细结构决定，其中高度硫酸化、富含艾杜糖醛酸的结构域与N - 乙酰化结构域交替出现。Syndecan - 4是一种细胞表面硫酸乙酰肝素蛋白聚糖，在细胞黏附中具有独特作用，这表明其链可能与其他细胞表面蛋白聚糖的链不同。为了确定syndecan - 4的特定作用是否与独特的硫酸乙酰肝素结构相关，我们分析了单个成纤维细胞株不同表面蛋白聚糖的硫酸乙酰肝素链，并比较了它们结合纤连蛋白Hep II结构域的能力，纤连蛋白是一种已知通过syndecan - 4促进粘着斑形成的配体。尽管磷脂酰肌醇蛋白聚糖和syndecan糖胺聚糖的分子量不同，二糖组成和硫酸化模式存在微小差异，但硫酸化区域的总体比例和分布以及对Hep II结构域的亲和力相似。因此，黏附调节需要syndecan - 4的核心蛋白决定簇。
