Conrad M E, Umbreit J N, Moore E G, Heiman D
University of South Alabama, Mobile 36688, USA.
J Clin Invest. 1996 Sep 15;98(6):1449-54. doi: 10.1172/JCI118933.
Iron is bound to transferrin in the plasma. A specific receptor on the cell surface binds transferrin and internalizes transferrin and the iron in clathrin-coated pits. These invaginate to form vesicles which release iron to the cytoplasm. Inorganic iron can be transported by an alternative pathway from iron citrate, utilizing a cell surface integrin and a cytoplasmic protein mobilferrin. This article shows that the two pathways donate iron to mobilferrin which acts as an intermediate between the iron bound to transferrin and the incorporation of iron into hemoglobin. Mobilferrin is found associated with the transferrin containing vesicles, and becomes labeled with iron released from transferrin in the vesicles. Mobilferrin is also found in the cytoplasm where pulse-chase experiments show that it, in turn, releases iron to be used for the synthesis of hemoglobin.
铁在血浆中与转铁蛋白结合。细胞表面的特定受体结合转铁蛋白，并将转铁蛋白和铁内化到网格蛋白包被的小窝中。这些小窝内陷形成囊泡，将铁释放到细胞质中。无机铁可以通过另一条途径从柠檬酸铁转运，利用细胞表面整合素和细胞质蛋白运铁蛋白。本文表明，这两条途径将铁提供给运铁蛋白，运铁蛋白在与转铁蛋白结合的铁和铁掺入血红蛋白之间起中间体的作用。发现运铁蛋白与含有转铁蛋白的囊泡相关，并在囊泡中被从转铁蛋白释放的铁标记。在细胞质中也发现了运铁蛋白，脉冲追踪实验表明，它反过来释放铁用于血红蛋白的合成。
