Kishimoto T, Tavassoli M
Biochim Biophys Acta. 1985 Jul 30;846(1):14-20. doi: 10.1016/0167-4889(85)90104-1.
Several studies using crude liver cell suspensions incubated with labeled transferrin have led to a conclusion that hepatocytes have transferrin receptors. When a visual probe, which permits evaluation of transferrin binding to individual cells, was used, the binding was unexpectedly found to be limited to endothelial cells in liver cell suspensions. Neither hepatocytes nor Kupffer cells contained transferrin receptors. In the present study, we fractionated liver cell suspensions using metrizamide gradients and centrifugal elutriation to obtain hepatocytes, Kupffer cell and endothelial cell fractions of high purity. Incubation of these fractions with 125I- or 59Fe-labeled transferrin led to exclusive binding to endothelial cells but not hepatocytes nor Kupffer cells. Kinetic analysis demonstrated Kd of 1.9 X 10(-7) M, Bmax of 3.1 pmol/10(6) cells per min, corresponding to 2.1 X 10(5) molecules/cell per min. At 4 degrees C, the binding reached a steady-state plateau within 5 min. Comparison of our data with those of previous investigators demonstrates a consistency if we consider that crude liver cell suspensions are contaminated with 2-3% endothelial cells. Thus, the previously reported findings may be entirely due to the contamination of crude liver cell suspensions with a small number of endothelial cells.
几项使用与标记转铁蛋白孵育的粗制肝细胞悬液的研究得出结论，肝细胞具有转铁蛋白受体。当使用一种允许评估转铁蛋白与单个细胞结合情况的视觉探针时，意外地发现结合仅限于肝细胞悬液中的内皮细胞。肝细胞和库普弗细胞均不含有转铁蛋白受体。在本研究中，我们使用甲泛葡胺梯度和离心淘洗法对肝细胞悬液进行分级分离，以获得高纯度的肝细胞、库普弗细胞和内皮细胞级分。用125I或59Fe标记的转铁蛋白孵育这些级分，结果显示转铁蛋白仅与内皮细胞结合，而不与肝细胞和库普弗细胞结合。动力学分析表明，解离常数（Kd）为1.9×10（-7）M，最大结合量（Bmax）为3.1 pmol/10（6）个细胞每分钟，相当于2.1×10（5）个分子/细胞每分钟。在4℃时，结合在5分钟内达到稳态平台。如果我们考虑到粗制肝细胞悬液被2%-3%的内皮细胞污染，将我们的数据与之前研究者的数据进行比较，结果显示是一致的。因此，先前报道的结果可能完全是由于粗制肝细胞悬液被少量内皮细胞污染所致。
