PLEIOTROPIC DEFENSES--THE HEMOPEXIN SYSTEM

描述（摘自申请人摘要） “多效性防御”一词在这里指的是生物系统 保护生物体免受一种以上有害物质的侵害， 条件 血液结合素系统的性质，其执行 受体介导的血红素转运通过血红素结合蛋白及其血浆的内吞 膜受体，使其成为这种保护机制的范例， 这两种蛋白质是R 03研究计划的重点。 的 血液结合蛋白系统作为免疫系统的一部分， 身体的防御机制，作为抗氧化剂在创伤，溶血 和炎症，从病原体螯合血红素，一个保守的， 细胞营养铁，以及保护蛋白质如铁蛋白的诱导剂， 金属硫蛋白。 所要求的两年支助的具体目标是：（1） 通过亲和层析分离足够人血红素结合蛋白受体， 允许：（a）受体的初始表征，即，分子 重量、亚基组成和糖基化，（B）特异性 高亲和力抗体的受体，使用商业服务 设施，和（c）克隆和测序人血红素结合蛋白的cDNA 受体，和（2）继续表征的结构决定因素 血红素结合蛋白-血红素结合蛋白受体相互作用。 为了实现这些目标，标准而强大的技术， 已经建立在这个实验室将采用，包括亲和力 用于受体分离的色谱法;全细胞、配体印迹和可溶性 受体结合测定; cDNA克隆和测序以及定点 诱变 我们还将获得用于未来结构研究的工具 和调节的受体和相互作用的基本信息， 血红素结合蛋白及其受体。 需要这些信息来开发 再灌注损伤等情况的治疗措施。 信息 对哺乳动物受体的研究也将补充对人类的研究 病原体细菌血红素结合蛋白受体，并提供设计所需的见解 是指选择性抑制细菌而非宿主的血红素结合蛋白受体。

DESCRIPTION (taken from the applicant's abstract) The term "pleiotropic defense" is used here to refer to biological systems that act to defend the organism against more than one deleterious agent or condition. The properties of the hemopexin system, which carries out receptor-mediated heme transport by endocytosis of hemopexin and its plasma membrane receptor, make it a paradigm for such protective mechanisms, and these two proteins are the foci of this R03 research proposal. The hemopexin system plays several distinct yet connected roles as part of the body's defense mechanisms, acting as an anti-oxidant in trauma, hemolysis and inflammation, a sequester of heme from pathogens, a conserver of the cell nutrient iron, and an inducer of protective proteins like ferritin and metallothionein. The specific aims for the two years of requested support are: (1) to isolate by affinity chromatography sufficient human hemopexin receptor to allow: (a) initial characterization of the receptor, i.e., molecular weight, subunit composition, and glycosylation, (b) production of specific high affinity antibodies to the receptor, using the services of a commercial facility, and (c) cloning and sequencing the cDNA for the human hemopexin receptor, and (2) to continue to characterize the structural determinants of the hemopexin-hemopexin receptor interaction. To accomplish these objectives, standard yet robust techniques that are already established in this laboratory will be employed, including affinity chromatography for receptor isolation; whole cell, ligand blot and soluble receptor binding assays; cDNA cloning and sequencing and site-directed mutagenesis. We will also obtain tools for future research on the structure and regulation of the receptor and basic information on the interaction of hemopexin with its receptor. Such information is needed to develop therapeutic measures for conditions like re-perfusion injury. Information on the mammalian receptor will also complement research on the human pathogen bacterial hemopexin receptors and provide insight needed to design means to selectively inhibit bacterial, but not host, hemopexin receptors.