FOLDING AND BINDING DETERMINANTS OF THE LDL RECEPTOR

描述：该项目的长期目标是提供一个 深入了解低密度脂蛋白受体（LDLR） 折叠成其天然结构并识别其脂蛋白配体。 LDLR是将血浆胆固醇摄取到血浆中的主要机制。 细胞当LDLR无法清除含胆固醇的 脂蛋白从血液中充分释放，血浆胆固醇升高 水平的结果。高血浆胆固醇水平是心脏病的主要风险 这种疾病是美国人死亡的主要原因。150多 LDLR的不同突变引起家族性高胆固醇血症 (FH)，其临床特征在于， 血浆LDL和胆固醇。 LDL-脂蛋白的详细结构和生化研究 相互作用是难以捉摸的，因为受体蛋白很大， 膜结合。然而，LDLR的配体结合结构域由 一系列自主结构的，不相同的串联重复序列， 可以从受体的其余部分中分离出来进行研究。前几 工作，PI已经表明，一个关键的重复（重复5）内， 受体的配体结合结构域可以折叠成其天然的 在细菌中表达后，钙是必需的， 正确折叠这个域。 在赠款支持期间，他计划（1）确定 这些原则支配着这种原型重复的正确折叠， LDLR配体结合结构域转化为其天然结构，和（2）阐明 LDLR结合配体的详细分子基础，依赖于 折叠研究，以确定受体-配体的潜在位点 互动这项工作将对生物多样性的机制产生广泛的影响。 配体相互作用这项工作将产生广泛的影响， 配体识别机制的各种蛋白质， 含有与配体结合中发现的结构基序同源的结构基序， LDLR的结构域，包括涉及G蛋白偶联的蛋白质 信号，大脑发育和免疫反应。了解 LDL-A重复序列识别配体的基础可能最终允许 改变LDL-A重复序列的配体结合特性， 用于任意靶配体的新型受体。最终，小分子 可以识别抑制折叠缺陷在一些FH 突变，并且可能作为FH患者的治疗方法。

DESCRIPTION: The long-term objective of this project is to provide a thorough understanding of how the low-density lipoprotein receptor (LDLR) folds into its native structure and recognizes its lipoprotein ligands. The LDLR is the primary mechanism for uptake of plasma cholesterol into cells. When the LDLR is unable to clear cholesterol-containing lipoproteins sufficiently from the blood, an elevated plasma cholesterol level results. A high plasma cholesterol level is a major risk for heart disease, the leading cause of death in the United States. Over 150 different mutations of the LDLR give rise to familial hypercholesterolemia (FH), which is characterized clinically by an elevated concentration of plasma LDL and cholesterol. Detailed structural and biochemical studies of LDLR-lipoprotein interactions have been elusive, because the receptor protein is large and membrane bound. However, the ligand-binding domain of the LDLR is composed of a series of autonomously structured, non-identical tandem repeats that can be studied in isolation from the rest of the receptor. In previous work, the PI has shown that a critical repeat (repeat 5) within the ligand-binding domain of the receptor can be folded to its native structure after expression in bacteria, and that calcium is required for proper folding of this domain. During the period of grant support, he plans (1) to determine the principles that govern proper folding of this prototypic repeat of the LDLR ligand-binding domain into its native structure, and (2) to elucidate the detailed molecular basis for ligand-binding by the LDLR, relying on the folding studies to identify potential sites of receptor-ligand interaction. This work will have broad implications for the mechanism of ligand interactions. This work will have broad implications for the mechanism of ligand recognition by the wide variety of proteins that contain structural motifs homologous to those found in the ligand-binding domain of the LDLR, including proteins implicated in G-protein couple signaling, brain development, and the immune response. Understanding the basis for ligand recognition by LDL-A repeats may ultimately allow the alteration of the ligand-binding properties of LDL-A repeats to create novel receptors for arbitrary target ligands. Eventually, small molecules may be identified which suppress the folding defects in some of the FH mutations, and which might serve as therapeutics for patients with FH.