RAMP-altered Class B GPCR Hormone Recognition

描述（由申请人提供）：人降钙素（CTR）和降钙素样（CLR）受体是细胞表面B类G蛋白偶联受体（gpcr），与受体活性修饰蛋白（RAMP）共受体结合，介导降钙素家族肽激素的信号传导。肽肾上腺髓质素（AM）、降钙素基因相关肽（CGRP）和amyin （AMY）的不同生物学作用是通过与由CLR或CTR和三种RAMPs之一组成的特定分子复合物结合而引起的。AM和CGRP分别通过CLR-RAMP2或3和CLR-RAMP1复合物调控心血管系统。AMY通过与RAMP1、2或3相关的CTR信号调节血糖水平。CLR/ cr - ramp复合物是重要的药物靶点。靶向CLR-RAMP复合物的治疗剂具有治疗急性心肌梗死、肺动脉高压、偏头痛、癌症和其他几种疾病的潜力。tr - ramp复合物是糖尿病药物SymlinTM的靶点。尽管靶向CLR/CTR-RAMP复合物具有临床价值，但肽激素识别和RAMP调节CLR/CTR激素特异性的分子机制尚不清楚，这在很大程度上是因为缺乏肽受体复合物的结构信息。激素结合的亲和力和特异性在很大程度上取决于CLR、CTR和RAMP整合膜蛋白的细胞外结构域（ECDs）。本提案的目标是确定AM， CGRP和AMY与其各自的CLR/CTR ECD- ramp ECD复合物结合的晶体结构，以确定确定选择性肽结合的精确分子结构。此外，我们将通过生化和基于细胞的药理学实验将结构和功能联系起来。我们提出以下三个目标：(1)确定人类CLR-RAMP2 ECD复合物识别AM的机制。(2)确定RAMP1如何赋予CLR-RAMP1 ECD复合物CGRP选择性。(3)确定人cr - ramp1 ECD复合物识别AMY的机制。实现这些目标将定义ramp改变的B类GPCR激素识别的分子基础，并提供结构模板来指导针对受体的治疗剂的合理设计。

DESCRIPTION (provided by applicant): The human calcitonin (CTR) and calcitonin-like (CLR) receptors are cell-surface class B G protein-coupled receptors (GPCRs) that associate with receptor activity modifying protein (RAMP) co-receptors to mediate signaling by calcitonin family peptide hormones. The distinct biological actions of the peptides adrenomedullin (AM), calcitonin gene-related peptide (CGRP), and amylin (AMY) are elicited by their binding to specific molecular complexes comprised of CLR or CTR and one of three RAMPs. AM and CGRP regulate the cardiovascular system by signaling through CLR-RAMP2 or 3 and CLR-RAMP1 complexes, respectively. AMY regulates blood glucose levels by signaling through CTR associated with RAMP1, 2, or 3. CLR/CTR-RAMP complexes are important drug targets. Therapeutic agents targeting CLR-RAMP complexes have the potential to treat acute myocardial infarction, pulmonary hypertension, migraine headache, cancer, and several other disorders. CTR-RAMP complexes are targets of the diabetes drug SymlinTM. Despite the clinical value of targeting CLR/CTR-RAMP complexes, the molecular mechanisms of peptide hormone recognition and RAMP modulation of CLR/CTR hormone specificity are poorly understood, in large part because of a lack of structural information for the peptide-receptor complexes. Hormone binding affinity and specificity are largely determined by the extracellular domains (ECDs) of the CLR, CTR, and RAMP integral membrane proteins. The goals of this proposal are to determine crystal structures of AM, CGRP, and AMY bound to their respective CLR/CTR ECD-RAMP ECD complexes in order to define the precise molecular architectures that determine selective peptide binding. In addition, we will correlate structure and function through biochemical and cell-based pharmacological experiments. We propose the following three aims: (1) Determine the mechanism of AM recognition by the human CLR-RAMP2 ECD complex. (2) Determine how RAMP1 confers CGRP selectivity to the CLR-RAMP1 ECD complex. (3) Determine the mechanism of AMY recognition by the human CTR-RAMP1 ECD complex. Achieving these aims will define the molecular bases for RAMP-altered class B GPCR hormone recognition and provide structural templates to guide the rational design of therapeutic agents targeting the receptors.