STRUCTURE/FUNCTION OF THE CCK-B/GASTRIN RECEPTOR

CCK-BR是一种7种跨膜受体 结构域多肽激素受体。它最重要的生理学特征之一 功能，CCK-BR调节胃酸分泌和粘膜增殖 在胃中以及在中央的焦虑和痛觉 神经系统。这种受体的潜在临床相关性 引起了人们对理解分子基础的极大兴趣 配体-CCK-BR相互作用。受体的突变分析， 在我们实验室进行的，表明存在配体结合 由跨膜结构域残基组成的口袋。非肽 苯二氮卓类配体似乎占据了这个假定的口袋。 这些化合物或氨基的微小结构修饰 构成受体口袋的酸可以影响这些 配体充当激动剂或拮抗剂。除了这些发现之外 对于非肽，我们已经获得了证据表明， 内源性多肽激动剂，胃泌素，是由相互作用产生的 跨膜和胞外区氨基酸之间的相互作用。在 目前的应用，我们建议进一步探索分子 与CCK-BR结合的配体决定因素和配体诱导的决定因素 受体激活，比较多肽和非多肽化合物。这个 胞外区和跨膜区的相对作用将 被探索。这笔赠款的具体目标1旨在确定 赋予配基亲和力的CCK-BR氨基酸。具体目标2 CCK-BR-配体相互作用影响能力的地址 诱导第二信使信号传递的配体。具体目标3将 利用我们实验室的最新发现，有组织地 活性CCK-BR与反式作用的化合物 激动剂，并因此减弱非配体依赖的信号。这些小说 工具将被用来探索受体-配体的相互作用 导致反向激动症。分子的组合(一代 嵌合和突变型受体，重组人瞬时表达 蛋白质)和药理学方法(放射性配基结合，第二 信使信令分析)将用于解决这些问题 目标。拟议的CCK-BR研究将建立一个 理解非肽配体如何模拟活性的框架 内源性多肽。此信息应扩展当前 对多肽激素构效关系的认识 一般的受体，因此在开发新的 通过这门课程为多种疾病提供治疗选择 蛋白质的含量。

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.