Binding of erythropoietin to CFU-E derived from fetal mouse liver cells.
Binding of erythropoietin to CFU-E derived from fetal mouse liver cells.
复制标题
促红细胞生成素与源自小鼠胎肝细胞的 CFU-E 的结合。
作者：
H. Fukamachi;T. Saito;A. Tojo;T. Kitamura;A. Urabe;F. Takaku
用放射性碘标记的衍生物研究了重组促红细胞生成素（EPO）与胎鼠肝细胞（FMLC）的结合。使用预先形成的Percoll密度梯度将FMLC分级。使用分级的FMLC，检查在半固体培养物中形成CFU-E集落的能力，并测量[125 I]EPO的结合。在密度为1.062 - 1.076 μ g/ml的组分中观察到[125 I]EPO的最高特异性结合。相同的级分显示出形成CFU-E衍生集落的最高能力。FMLC与EPO悬浮培养2天后，分化的红系细胞密度明显增加。[125 I]EPO与这些细胞的特异性结合几乎随着分化而消失。用CFU-E富集级分的细胞进行的Scatchard分析显示出非线性曲线，表明存在两类结合位点。一个结合位点是高亲和力的（Kd 1 = 0.41 nM），另一个是低亲和力的（Kd 2 = 3.13 nM）。这些结果表明红系细胞上EPO受体的表达在CFU-E中最高。
The binding of recombinant erythropoietin (EPO) to fetal mouse liver cells (FMLC) was investigated using a radioiodinated derivative which retained full biological activity. FMLC were fractionated using a preformed Percoll density gradient. Using the fractionated FMLC, the ability to form CFU-E colonies in a semisolid culture was examined, and the binding of [125I]EPO was measured. The highest specific binding of [125I]EPO was observed in a fraction with a density between 1.062 and 1.076 g/ml. The same fraction showed the highest ability to form CFU-E-derived colonies. After suspension culture of FMLC with EPO for 2 days, differentiated erythroid cells with higher density markedly increased. The specific binding of [125I]EPO to these cells almost disappeared with differentiation. Scatchard analysis with cells of the CFU-E-enriched fraction showed a nonlinear curve, suggesting the existence of two classes of binding sites. One binding site was high-affinity (Kd1 = 0.41 nM), and the other low-affinity (Kd2 = 3.13 nM). These results suggest that the expression of EPO receptors on the erythroid cells is highest in CFU-E.