Lactisole inhibits the sweet taste receptor

描述（由申请人提供）：甜味感觉由甜味受体T1 R2 + T1 R3介导，T1 R2 + T1 R3是T1 Rs家族的两种密切相关的G蛋白偶联受体。T1 R2 + T1 R3是一种广泛调节的受体，对所有类型的甜味化合物都有反应。T1 R具有大的细胞外结构域、7-跨膜（7 TM）和短的C-末端尾。本申请的目的是使用分子生物学和甜味抑制化合物lactisole阐明人T1 R3的结构-功能关系。我将利用lactisole作用于人T1 R3 7 TM，但不作用于小鼠T1 R3的事实。目的1是利用人/小鼠T1 R3嵌合体和定点突变来鉴定对lactisole对人T1 R3的抑制作用至关重要的人特异性TM区域和残基。目的2是通过参考类似的GPCR 7 TM结构（包括牛视紫红质、mGluRs和细胞外钙敏感受体）来确定包含lactisole结合口袋的其他残基。这些发现将用于完善人T1 R3的7 TM模型。了解T1 R3的结构/功能关系可能有助于开发新型低热量甜味剂，以帮助对抗肥胖和糖尿病等饮食相关疾病。

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.