Dekker C J, Kroos M J, Van der Heul C, Van Eijk H G
Int J Biochem. 1985;17(6):701-6. doi: 10.1016/0020-711x(85)90368-4.
Incubation of isolated rat hepatocytes with different human sialo transferrins shows that interaction with the specific transferrin receptor is insensitive to differences in the carbohydrate composition of the glycans. Asialo transferrins lead to an increased iron uptake, which is dependent on the amount of exposed galactose. This is explained by the presence of the asialo glycoprotein (AsGP) receptor. Experiments with selective saturation of the two receptor systems show that on incubation with human asialo transferrin (AsHTf) transferrin uptake proceeds increasingly via the AsGP receptor on raising the concentration. Homologous rat asialo transferrin (AsRTf) behaves similarly, but less pronounced. Iron is accumulated via both receptor systems in the heterologous system, but only via the transferrin receptors in the homologous system. The difference in interaction with the AsGP-receptor may be caused by the difference in galactose content of the two asialo transferrins. As an explanation for the differences in intracellular metabolism a hitherto unknown recognition system for species specificity is postulated which protects homologous AsRTf from degradation, but directs foreign AsTf to lysosomes.
将分离的大鼠肝细胞与不同的人唾液酸转铁蛋白一起孵育表明，与特异性转铁蛋白受体的相互作用对聚糖碳水化合物组成的差异不敏感。去唾液酸转铁蛋白会导致铁摄取增加，这取决于暴露的半乳糖量。这可以通过去唾液酸糖蛋白（AsGP）受体的存在来解释。对两种受体系统进行选择性饱和的实验表明，在与人去唾液酸转铁蛋白（AsHTf）孵育时，随着浓度升高，转铁蛋白摄取越来越多地通过AsGP受体进行。同源大鼠去唾液酸转铁蛋白（AsRTf）表现类似，但不太明显。在异源系统中，铁通过两种受体系统积累，但在同源系统中仅通过转铁蛋白受体积累。与AsGP受体相互作用的差异可能是由两种去唾液酸转铁蛋白半乳糖含量的差异引起的。作为细胞内代谢差异的一种解释，推测存在一种迄今未知的物种特异性识别系统，该系统可保护同源AsRTf不被降解，但将外来AsTf导向溶酶体。
