Functional study on large glycans on the surface of developing embryos

为了解决一个问题，为什么巨大的聚糖附着在胚胎细胞表面，我们研究了两个我们自己在马达卡鱼中发现的糖蛋白的例子。首先，成功地纯化了含有lex大聚糖的蛋白，命名为LeX-gp。聚糖被证明含有lex结构的多重串联重复序列，并参与细胞粘附。其次，发现卵在受精时分泌的卵皮质泡状糖蛋白，即垂体磷脂蛋白，参与了卵皮质反应或卵活化以及水母早期发育的进程。我们发现肽部分通过与特定受体的结合对其细胞增殖刺激活性很重要，而聚糖部分则更需要皮质反应而不是胚胎细胞的细胞生长。综上所述，我们提出了一个假设，即一旦与细胞表面相关联，巨大的聚糖就会急剧改变表面气氛，从而显著影响细胞的生理机能。

To address a question why the extremely large glycans are attached on the embryonic cell surface, we studied on two examples of glycoprotein that had been found in madaka fish by ourselves. First, the protein with LeX-containing large glycans, named LeX-gp, was successfully purified. The glycans were shown to contain a multiply tandem repeat of LeX-structure, and to be involed in cell adhesion. Second, the egg cortical vesicular glycoprotein that is secreted from egg at fertilization, named hyosophorin, was found to be involved in cortical reaction or egg activation and the progress of early development of medaka. We revealed that the peptide part is important for its cell proliferation stimulating activity through its binding to a specific receptor, while the glycan part is rather required for the cortical reaction than for the cell growth of embryonic cells. Taken together, we postulate a hypothesis that , once associated with the cell surface, the huge glycans drastically change the surface atmosphere to affect the physiology of cell significantly.