Structural Biology of Class B G-Protein Coupled Receptors

该项目的长期目标是解开激素结合和激活的结构基础， B类G蛋白偶联受体（GPCR）家族，并探索获得的结构信息 其目标是合理设计肽激素来治疗人类疾病。B类促胰液素家族 GPCR在人类中由15个成员组成，包括甲状旁腺激素（PTH）受体、胰高血糖素受体和胰高血糖素受体。 (GCG)胰高血糖素样肽-1（GLP 1）和促肾上腺皮质激素释放因子（CRF）。这些肽激素 已知在代谢稳态和骨骼系统的完整性中起关键作用。因此，类 B GPCR是公认的药物靶标。PTH片段（残基1-34）和GLP 1类似物（毒蜥外泌肽-4， 分离自蜥蜴毒液）已被用于治疗骨质疏松症和II型糖尿病。然而，在这方面， 这些肽类似物的临床应用受到副作用的限制 结合亲和力或低药理学稳定性。B类药物高效选择性配体的发现 GPCR仍然是药物研究的重要目标。 B类GPCR含有N-末端胞外结构域（ECD），其负责特异性激素 识别.因此，ECD一直是密集的结构研究的焦点。直到最近， 受体ECD/激素复合物的合成受到技术困难的阻碍。这种有限的结构 考虑到B类GPCR及其激素在正常人中的重要性， 生理学和疾病。在这项研究中，我们建议通过解决晶体结构来填补这一知识空白， 几种治疗上重要的B类GPCR ECD与其相应的肽激素结合。我们 具体的目的集中在结合于PTH，PTHrP， TIP39结构确定后，我们将仔细检查和分析结构，以确定关键结构 元件，我们将通过定点诱变评估这些元件的功能意义， 生物化学结合测定。这些研究将提供激素识别的分子基础， 药物发现的合理模板。 PHS 398/2590（Rev. 11/07） 项目负责人/主要研究者（最后，第一，中间）：徐，H。埃里克

The long-term objectives of this project are to unravel the structural basis of hormone binding and activation of the family of Class B G-protein-coupled receptors (GPCRs) and to explore the obtained structural information with a goal toward rational design of peptide hormones to treat human diseases. The secretin family of Class B GPCRs consists of 15 members in humans, including receptors for parathyroid hormone (PTH), glucagon (GCG), glucagon-like-peptide-1 (GLP1), and corticotropin-releasing factor (CRF). These peptide hormones are known to play crucial roles in metabolic homeostasis and the integrity of skeleton systems. As such, Class B GPCRs are well-established drug targets. A PTH fragment (residues 1-34) and a GLP1 analog (exendin-4, isolated from lizard venom) have been used for the treatment of osteoporosis and type II diabetes. However, the clinical use of these peptide analogs is limited by side effects, partly associated with their low receptor binding affinity or low pharmacological stability. The discovery of highly potent and selective ligands for Class B GPCRs remains an important goal of pharmaceutical research. The Class B GPCR contains an N-terminal extracellular domain (ECD) that is responsible for specific hormone recognition. As such the ECD has been the focus of intense structural study. Until recently, structure solution of a receptor ECD/hormone complex has been hindered by technical difficulties. This limited structural information is a serious deficiency considering the importance of Class B GPCRs and their hormones in normal physiology and in disease. In this study, we propose to fill this knowledge gap by solving the crystal structures of several therapeutically important Class B GPCR ECDs bound to their corresponding peptide hormones. Our specific aims are focused on structural determination of the ECD of PTH1R and PTH2R bound to PTH, PTHrP, and TIP39. After structural determination, we will scrutinize and analyze the structures for key structural elements, and we will assess the functional significance of those elements by site-directed mutagenesis and biochemical binding assays. These studies will provide the molecular basis of hormone recognition and a rational template for drug discovery. PHS 398/2590 (Rev. 11/07) Page Continuation Format Page Program Director/Principal Investigator (Last, First, Middle): Xu, H. Eric