Lactisole inhibits the sweet taste receptor

描述(申请人提供)：甜味感觉是由甜味受体T1R2+T1R3介导的，T1R2+T1R3是T1Rs家族中两个密切相关的G蛋白偶联受体。T1R2+T1R3是一种广泛调节的受体，对所有种类的甜味化合物都有反应。T1Rs具有较大的胞外结构域、7-跨膜(7TM)和较短的C-末端尾巴。本应用的目的是利用分子生物学和抑制甜味的化合物乳糖醇来阐明人T1R3的结构和功能关系。我将利用乳素作用于人的T1R37TM，而不是作用于小鼠T1R3的事实。目的1利用人/鼠T1R3嵌合体和定点突变技术，鉴定乳素对人T1R3抑制作用的人特异性TM区域和残基。目的2是通过参考类似的GPCR7TMS结构，包括牛视紫红质、mGluRs和细胞外钙感受器，确定组成乳糖醇结合口袋的其他残基。这些发现将被用于改进人类T1R3的7个TM的模型。对T1R3结构/功能关系的了解可能有助于开发新型的低热量甜味剂，以帮助对抗与饮食相关的疾病，如肥胖和糖尿病。

DESCRIPTION (provided by applicant): The sense of sweet taste is mediated by the sweet taste receptor, T1R2+T1R3, which are two closely related G protein-coupled receptors of T1Rs family. T1R2+T1R3 is a broadly tuned receptor responding to all classes of sweet compounds. T1Rs have a large extracellular domain, 7-transmembranes (7TMs), and a short C-terminal tail. The goal of this application is to elucidate structure-function relationships of human T1R3 using molecular biology and the sweet suppressing compound lactisole. I will take advantage of the fact that lactisole acts on human T1R3 7TMs, but not on mouse T1R3. Aim 1 is to identify the human-specific TM regions and residues that are critical for lactisole's inhibitory effect on human T1R3 using human/mouse T1R3 chimeras and site-directed mutagenesis. Aim 2 is to determine other residues comprising the lactisole binding pocket by referring to similar GPCR 7TMs structures including bovine rhodopsin, mGluRs, and the extracellular calcium sensing receptor. These findings will be used to refine a model of 7TMs of human T1R3. Knowledge of the structure/function relationship of T1R3 may assist in the development of novel, low caloric sweeteners to help fight against diet-related disorders such as obesity and diabetes.