LIGAND BINDING DOMAINS OF ANGIOTENSIN RECEPTORS

描述：血管紧张素(AT)受体拮抗剂有望成为一种 治疗控制某些形式的高血压的策略。许多 有效的抗高血压非肽AT1受体拮抗剂 过去几年发展起来的有复杂的作用机制。 仍然需要更好地理解这些属性 由于需要更安全和更有选择性的药物，化合物可能会出现在 未来。实现这一点的一种方法是开发AT1的模型 受体结构。直到取得意想不到的技术进步 在纯化和结晶完整的膜受体蛋白时， 受体结构的模型仍然可以通过结合位点- 通过结构-活性-关系(SAR)分析进行定向突变。 这项研究的基本目标是通过以下方式开发这样的模型 鉴定目前可用的AT多肽和AT的分子相互作用 含AT受体的非肽类化合物。更长期的好处 而这项研究的最终考验将是新药的生产 根据空间预测合理设计结构 AT受体结构域的排列。结果可能会更多 泛指对结构性预测的效用的检验 用于针对这一大类蛋白质的药物设计和开发。 提出假设是为了：1)检验残基存在于 AT受体胞外区与AT多肽的关系 相互作用，不同于G蛋白偶联受体 胺；2)鉴定非肽的受体结合部位 了解苯并咪唑拮抗剂的配体和作用力 受体与这些化合物之间的相互作用和3)确定 多肽和非肽对AT受体不可逾越的拮抗作用 拮抗剂是药物不平衡的结果，而不是复杂的 并了解变构作用的结构和分子基础 不可逾越的对立。为了开始解决这些问题， AT受体的药理、功能和分子多样性 物种亚型将被用来识别结构域和特定的 受体中与其分化相关的氨基酸残基 表型。突变策略，包括交换发散的 提出了不同AT受体亚型之间的氨基酸残基 作为鉴定这些结合结构域的第一步。曾经的遗址 通过这种比较方法建立了配体联系，并 将采用实证的方法来完善模型，揭示其他 与所有AT受体共同的配体接触的残基 异构体，并确定这些异构体的特异性和作用力 受体-配体相互作用。为了实现这一点，突变的影响 在比较法确定的邻近地点，将 被分析。一系列点突变在任何单个 然后将使用放射性配基结合和 功能性SAR研究，采用了一系列不同的多肽和非 多肽配体衍生物。将采用类似的方法来 揭示AT受体不可逾越的拮抗机制 为了建立区别于它的分子决定因素 不可战胜的对抗性。

DESCRIPTION: Angiotensin (AT) receptor antagonism shows promise as a strategy for therapeutic control of some forms of hypertension. Many of the effective, antihypertensive non-peptide AT1 receptor antagonists developed over the past several years have complex mechanisms of action. A need still exists to understand better the properties of these compounds as a need for more safe and selective drugs may arise in the future. One means of achieving this is to develop a model of AT1 receptor structure. Until unforeseen technological advances are made in purifying and crystallizing integral membrane receptor proteins, models of receptor structure can still be developed by combining site- directed mutagenesis with structure-activity-relationship (SAR) analysis. The fundamental goal of this research is to develop such a model by identifying molecular interactions of currently available AT peptides and non- peptide compounds with the AT receptors. The longer term benefit and ultimate test of this research would be the production of novel drug structures designed rationally from predictions of the spatial arrangement of AT receptor domains. The outcomes may be even more broadly generalized as a test for the utility of structural predictions for drug design and development for this broad class of proteins. Hypotheses are proposed to: 1) test the possibility that residues in extracellular domains of AT receptors are involved in AT peptide interactions, unlike for G-protein coupled receptors for biogenic amines; 2) to identify the receptor binding sites for the non-peptide phenylimidazole antagonist ligands and to understand the forces of interactions between the receptor and these compounds and 3) to determine if insurmountable antagonism of AT receptors by peptide and non-peptide antagonists results from a pharmacologic disequilibrium and not complex allostericism and to understand the structural and molecular basis for insurmountable antagonism. To begin to address these issues, the pharmacological, functional and molecular diversity of AT receptor species isoforms will be exploited to identify domains and specific amino acid residues in the receptors associated with their divergent phenotypes. Mutagenic strategies that include the exchange of divergent amino acid residues among differing AT receptor isoforms, are proposed as a first step in identifying these binding domains. Once sites of ligand contact have been established by this comparative approach, an empirical approach will be employed to refine the model, to reveal other residues that contact ligand which are common to all AT receptor isoforms, and to determine the specificity and forces dictating these receptor-ligand interactions. To achieve this, the effects of mutations at sites neighboring those identified by the comparative approach will be analyzed. The effects of a series of point mutations at any single of these sites will then be analyzed using radioligand binding and functional SAR studies, employing a diverse array of peptide and non- peptide ligand derivatives. Similar approaches will be employed to reveal the mechanisms of insurmountable antagonism of AT receptors, and to establish the molecular determinants that differentiate it from surmountable antagonism.