STRUCTURE/FUNCTION OF THE CCK-B/GASTRIN RECEPTOR

CCK-B/胃泌素受体的结构/功能

• 批准号: 2620355
• 负责人: ALAN S KOPIN
• 金额: $ 23.47万
• 依托单位: TUFTS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-09-30 至 2003-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2620355
• 关键词: G protein; autoradiography; chemical models; cholecystokinin; gastrins; hormone receptor; neuropeptide receptor; polymerase chain reaction; protein sequence; protein structure function; receptor binding; receptor coupling; receptor expression; second messengers; site directed mutagenesis; tissue /cell culture

The cholecystokinin-B/gastrin receptor (CCK-BR) is a seven transmembrane domain peptide hormone receptor. Among its most important physiologic functions, the CCK-BR modulates acid secretion and mucosal proliferation in the stomach as well as anxiety and pain perception in the central nervous system. The potential clinical relevance of this receptor has generated considerable interest in understanding the molecular basis of ligand - CCK-BR interactions. Mutational analysis of the receptor, carried out in our laboratory, suggests he existence of a ligand binding pocket comprised of transmembrane domain residues. Non-peptide benzodiazepine-based ligands appear to occupy this putative pocket . Minor structural modifications either of these compounds or of the amino acids which comprise the receptor pocket , can influence whether these ligands act as agonists or antagonists. In addition to these findings with non-peptides, we have obtained evidence that affinity for the endogenous peptide agonist, gastrin, is conferred by an interaction between trans-membrane and extracellular domain amino acids. In the current application, we propose to further explore the molecular determinants of ligand binding to the CCK-BR, and of ligand-induced receptor activation, comparing peptide and non-peptide compounds. The relative roles of both the extracellular and transmembrane domains will be explored. Specific Aim 1 of this grant is directed toward defining CCK-BR amino acids which confer ligand affinity. Specific Aim 2 addresses which CCK-BR -ligand interactions influence the ability of the ligand to induce second messenger signaling. Specific Aim 3 will exploit the recent discoveries in our laboratory of a constitutively active CCK-BR together with a compound that functions as an inverse agonist and as such attenuates ligand-independent signaling. These novel tools will be utilized to explore the receptor-ligand interactions which result in inverse agonism. A combination of molecular (generation of chimeric and mutant receptors, transient expression of recombinant proteins) and pharmacologic methods (radioligand binding, second messenger signaling assays) will be utilized to address these objectives. The proposed studies of the CCK-BR will establish a framework for understanding how non-peptide ligands mimic the activity of endogenous peptides. This information should expand current knowledge of structure-function relationships of peptide hormone receptors in general and may therefore be useful in developing new therapeutic options for a wide range of diseases mediated by this class of proteins.

胆囊收缩素-B/胃泌素受体（CCK-BR）是一种七跨膜的多肽， 结构域肽激素受体。 其中最重要的生理 功能，CCK-BR调节酸分泌和粘膜增殖 以及中枢神经系统的焦虑和疼痛感知 神经系统 该受体的潜在临床相关性 产生了相当大的兴趣，了解分子基础， 配体- CCK-BR相互作用。 受体的突变分析， 在我们的实验室进行，表明存在配体结合 由跨膜结构域残基组成的口袋。 非肽 基于苯并二氮杂卓的配体似乎占据了这个推定的口袋。 这些化合物或氨基的微小结构修饰 酸，包括受体口袋，可以影响这些是否 配体作为激动剂或拮抗剂。 除了这些发现之外， 与非肽，我们已经获得的证据表明，亲和力的 内源性肽激动剂，胃泌素，是由一种相互作用 跨膜和胞外区氨基酸之间的联系。 在 目前的应用，我们建议进一步探索分子 配体与CCK-BR结合的决定因素，以及配体诱导的 受体活化，比较肽和非肽化合物。 的 胞外和跨膜结构域的相对作用将 被探索。 该补助金的具体目标1旨在定义 赋予配体亲和力的CCK-BR氨基酸。 具体目标2 地址CCK-BR -配体相互作用影响的能力， 配体以诱导第二信使信号传导。 第3章将 利用我们实验室最近的发现， 活性CCK-BR与起反相作用的化合物一起 激动剂，并因此减弱配体非依赖性信号传导。这些新颖 将利用工具来探索受体-配体相互作用， 导致反向激动作用。 分子的组合（产生 嵌合型和突变型受体，重组体的瞬时表达 蛋白质）和药理学方法（放射性配体结合，第二 信使信号分析）将用于解决这些问题 目标. CCK-BR的拟议研究将建立一个 理解非肽配体如何模拟活性的框架 内源性肽。 此信息应扩展当前 肽类激素构效关系知识 受体，并因此可用于开发新的 这类疾病介导的广泛疾病的治疗选择 蛋白质。