ROLE OF HEME-BINDING PROTEINS IN HEPATIC HEME TRANSPORT

血红素通过血凝素向肝脏的转运具有重要意义 对肝细胞的影响。不仅在生物学上可用 铁的保存和外周血红素的毒性作用被预防，但也 运输的血红素调节参与蛋白的表达。 血红素、血红素蛋白和铁的代谢。这样做的最终目的是 研究项目旨在阐明该系统的作用和作用机制。 多聚体、膜血红素结合蛋白(MHBP) 肝脏对血红素的摄取、细胞内血红素转运和基因调控 用亚铁血红素。为了实现这一研究计划的目标，一个基本的 正在采取的方法是分离MHBP的亚基 以及它们在细胞内血红素转运中的作用 以及对蛋白质表达的调控。 所请求的5年支持的具体目标是： 1.继续研究具有重要生物化学意义的分子 MHBP及其亚基p17.5(与血红素结合)和p47的性质； 2.继续阐明MHBP在全球的作用和机制 肝细胞内血红素转运的生物化学和生物化学研究 形态方法； 3.继续通过以下方式确定肝脏蛋白质的调节 受体介导的血红素及其类似物的转运； 4.克隆和测序血红素结合亚基p17.5的基因 使用可用的抗体，从手头的肝脏cDNA库中获得MHBP 或寡核苷酸探针；以及 5.利用所克隆的针对MHBP p17.5基因的cDNA对其进行初步研究。 表情。 有几种蛋白质已经进化到与血红素结合，以便引导 这种难溶的高活性铁的化学 分子。从研究中获得的基本信息 在MHBP上提出的建议将提供基本问题的答案 关于健康人肝内血红素和铁代谢的动态平衡 和疾病。

The transport of heme to the liver by hemopexin has important consequences for the hepatocyte. Not only is biologically available iron conserved and toxic effects of peripheral heme prevented but also the transported heme regulates the expression of proteins involved in heme, heme-protein and iron metabolism. The ultimate goal of this research project is to elucidate the role and mechanism of action of the multimeric, membrane heme-binding protein (MHBP) of the hemopexin system in hepatic heme uptake, intracellular heme transport and gene regulation by heme. To achieve the goals of this research program, a basic approach is being taken in which the subunits of MHBP are being isolated and characterized, and their function in intracellular heme transport and regulation of protein expression delineated. The specific aims for the 5 years of requested support are: 1. To continue to characterize biochemically important molecular properties of MHBP and its subunits, p17.5 (which bind heme) and p47; 2. To continue to delineate the role and mechanism of action of MHBP in intracellular heme transport by liver cells employing biochemical and morphological approaches; 3. To continue to define the regulation of hepatic proteins by receptor-mediated transport of heme and heme analogs; 4. To clone and sequence the cDNA for p17.5, the heme-binding subunit of MHBP, from liver cDNA libraries in hand, using available antibodies or oligonucleotide probes; and 5. To use the cloned cDNA to p17.5 of MHBP to investigate its expression. Several proteins have evolved to bind heme in order to direct the chemistry of the highly-reactive iron of this poorly water-soluble molecule. The basic information to be obtained from the research proposed here on MHBP will provide answers to fundamental questions concerning the homeostasis of hepatic heme and iron metabolism in health and disease.