MECHANISMS OF CELLULAR IRON UPTAKE FROM TRANSFERRIN

尽管近年来对铁代谢的理解取得了巨大进展，但哺乳动物细胞中铁转运和体内平衡的调控仍有待发现。目前的研究重点是转铁蛋白和转铁蛋白受体在铁依赖细胞的铁转运管理中的作用。提出了两种协作努力和一种基本上是独立的努力。在第一个项目中，主要是与项目2的合作研究，重点是转铁蛋白受体的转铁蛋白识别位点。铁需求细胞的转铁蛋白受体不仅具有结合和内化转铁蛋白的功能，还具有调节铁从转铁蛋白中释放的功能。我们的目标是确定受体如何识别和结合转铁蛋白，受体-转铁蛋白复合物如何抵抗其内化的酸化内体的破坏，以及受体如何以ph依赖的方式调节转铁蛋白的铁释放。接下来，在我们的主要工作中，我们试图通过确保转铁蛋白载体铁的转移，了解肝细胞表现出的受体不依赖途径中的分子事件。这种途径可能比更好理解和更经常研究的受体介导的途径为肝细胞提供更多的铁。在我们的第三个项目中，我们将与项目5共同努力，探索转铁蛋白结合和释放铁的构象变化。在这里，我们的目的是揭示转铁蛋白构象变化的序列和机制。在这里，我们的目标是揭示转铁蛋白构象变化的序列和机制。我们的方法是以问题为导向，多学科结合细胞生物学、分子生物学（诱变）和物理生物化学的方法来了解铁代谢的基本生物学过程。

Although recent years have seen tremendous strides in the understanding of iron metabolism, which remains to be uncovered about the regulation of iron transport and homeostasis in mammalian cells. The present study focuses on the roles of transferrin and the transferrin receptor in managing the delivery of iron to iron-dependent cells. Two collaborative efforts, and one that is largely self-contained, are presented. In the first of these, a largely collaborative study with Project 2 of the Program, the emphasis is on the transferrin-recognition site of the transferrin receptor. The transferrin receptor of iron-requiring cells functions not only to bind and internalize transferrin, but also to modulate iron release from transferrin. Our goal is to determine how the receptor recognizes and binds transferrin, how the receptor-transferrin complex resists disruption within the acidified endosome to which it is internalized, and how the receptor regulates iron release from transferrin in a pH-dependent fashion. Next, in our major undertaking, we seek to understand the molecular events in the receptor-independent pathway exhibited by hepatic cells by securing transferring transferrin- borne iron. This pathways may secure more iron for hepatocytes than the much better understood, and more often studied, receptor-mediated route. In our third undertaking, a joint effort with Project 5 of the Program, we will explore the conformational changes accompanying the binding and release of iron by transferrin. Here, our aim is to unravel the sequences and mechanisms of conformational changes in transferrin. Here, our aim is to unravel the sequences and mechanisms of conformational changes in transferrin Our approach is problem-oriented and multi- disciplinary combining methods of cell biology, molecular biology (mutagenesis), and physical biochemistry to gain information into the fundamental biological processes of iron metabolism.