MECHANISM OF AGONISM-ANTAGONISM OF SWEET TASTE RECEPTORS

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 目前的建议的目标是开发可能的结合位点的分子模型内的跨膜（TM）结构域的人甜味受体，人T1 R2（hT 1 R2）和hT 1 R3的异二聚体，这属于G蛋白偶联受体家族的激动剂和拮抗剂。最近的晶体结构的牛视紫红质提供了一个机会，构建模型的GPCR已被证明是可靠的预测的选择性和这些受体的活性。我们假设：1.激动剂和拮抗剂结合在相同的TM口袋中;和2.通过结合，激动剂诱导导致激活的特异性构象变化，并被拮抗剂的结合阻断。我们将鉴定人工甜味剂受体中的结合口袋（例如，环己基氨基磺酸盐）和抑制剂，（例如，lactisole），并通过诱变研究测试它们的有效性。实验证实的模型将被用来进行分子动力学模拟占用和未占用的受体开发的甜味反应的激活和抑制机制的分子基础的理解。从模拟中推断的机制将通过设计用于产生组成型活性受体的突变进行测试。这些研究将有助于更好地了解受体功能，并为设计新型甜味调节剂提供基础。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The goal of the current proposal is to develop molecular models of possible binding sites for agonists and antagonists within the transmembrane (TM) domain of the human sweet taste receptor, the heterodimer of human T1R2 (hT1R2) and hT1R3, which belongs to the G protein coupled receptor family. Recent crystal structures of bovine rhodopsin provide an opportunity to construct models of GPCRs that have been shown to be reliable predictors of selectivity and of activity in these receptors. We hypothesize that: 1. Agonists and antagonists bind in the same TM pocket; and 2. Through binding, agonists induce specific conformational changes that lead to activation and are blocked by the binding of antagonists. We will identify the binding pockets in the receptor for artificial sweeteners, (e.g., cyclamate) and inhibitors, (e.g., lactisole) by computational molecular docking and test their validity via mutagenesis studies. The experimentally confirmed models will be used to conduct molecular dynamics simulations on occupied and unoccupied receptors to develop an understanding of the molecular basis for activation and inhibition mechanisms of the sweet taste response. The mechanisms inferred from simulations will be tested by mutations designed to produce a constitutively active receptor. These studies should lead to a better understanding of receptor function and will provide the basis for design of novel sweet taste modulators.