糖链结构不同的纤连蛋白与HT1080细胞结合研究

Binding of Fibronectin with Different N-Oligoglycans to HT1080 Cells

人血浆纤连蛋白（Ｆｉｂｒｏｎｅｃｔｉｎ，Ｆｎ）与人胎盘纤连蛋白两者在肽链结构上基本相同，但人血浆Ｆｎ的Ｎ－糖链结构为二天线结构，而人胎盘Ｆｎ不仅Ｎ－糖链的数量增加，同时还含有多天线结构，分别用^（１２５）Ｉ标记这两种具有不同糖链结构的Ｆｎ，观察两者与ＨＴ１０８０细胞的饱和结合的亲和性，结果发现，在４℃，人血浆Ｆｎ与ＨＴ１０８０细胞的饱和结合为１２９ｎｇ／１０~５细胞，解离常数为２．８３×１０^（－８）ｍｏｌ／Ｌ，人胎盘Ｆｎ与ＨＴ１０８０细胞的饱和结合为１３３ｎｇ／１０~６细胞，解离常数为２．６４×１０^（－８）ｍｏｌ／Ｌ．因而，人血浆Ｆｎ与人胎盘Ｆｎ上Ｎ－糖链的不同并未影响其与受体的结合．

The fibronectin from human plasma and placenta have almost identical structures in the protein moiety. But the N-glycan of plasma Fn is biantennary and the N-glycan of placenta Fn has the triantennary and tetraantennary structures. These two kinds of Fn were labeled with ￣(125)I,and their saturation binding and binging affinity to HT1080 Cells were assayed. We found that (1 ) the saturated binding amount of plasma Fn to HT1080 cells is 129 ng/10￣6 cells,K_d =2. 83 × 10￣(-8) 6 mol/L. (2) the saturated binding amount of placenta Fn is 133 ng/10￣6 cell ,Kd =2. 64 × 10￣(-8)mol/L. So it can be concluded that the different N-glycan structure of the two kinds of Fn did not affect their interaction with the Fn receptor on cell surface.