Vanderpuye O A, Kelley L K, Smith C H
Placenta. 1986 Sep-Oct;7(5):391-403. doi: 10.1016/s0143-4004(86)80027-3.
Transferrin was identified in a preparation of human syncytiotrophoblast basal plasma membrane. Such transferrin was shown to be bound to an amphiphilic membrane protein of subunit mol.wt 94 000 by crossed hydrophobic interaction immunoelectrophoresis and immunoprecipitation with antibodies to transferrin. Basal plasma membrane bound 125I-labelled transferrin in a saturable, reversible manner with high affinity (Kd = 2.5 +/- 0.6 X 10(-9) M). The maximum binding capacity (0.9 +/- 0.2 pmol transferrin/mg membrane protein) was approximately a half of that of microvillous membrane. The basal membrane transferrin receptors were similar to microvillous receptors in that their affinity for diferric transferrin was higher than that for apo-transferrin and transferrin dissociation was negligible at pH 5.0 but rapid at pH 7.4. We conclude that syncytiotrophoblast basal plasma membrane possesses a receptor similar, if not identical, to that on the microvillous membrane. These receptors are thus in a position to participate in iron transfer to the fetus or potentially to have alternative functions in the syncytiotrophoblast.
在人合体滋养层基底质膜的制备物中鉴定出了转铁蛋白。通过交叉疏水相互作用免疫电泳以及用抗转铁蛋白抗体进行免疫沉淀，发现这种转铁蛋白与一种亚基分子量为94000的两亲性膜蛋白结合。基底质膜以可饱和、可逆且高亲和力（Kd = 2.5 +/- 0.6×10⁻⁹ M）的方式结合¹²⁵I标记的转铁蛋白。最大结合容量（0.9 +/- 0.2 pmol转铁蛋白/毫克膜蛋白）约为微绒毛膜的一半。基底膜转铁蛋白受体与微绒毛受体相似，即它们对双铁转铁蛋白的亲和力高于对脱铁转铁蛋白的亲和力，并且在pH 5.0时转铁蛋白解离可忽略不计，但在pH 7.4时迅速解离。我们得出结论，合体滋养层基底质膜拥有一种与微绒毛膜上的受体相似（即便不完全相同）的受体。因此，这些受体能够参与铁向胎儿的转运，或者可能在合体滋养层中具有其他功能。
