Monellin activates the human sweet taste receptor

描述（由申请人提供）：甜味受体由单体T1 R2 + T1 R3组成，是哺乳动物中负责甜味的主要受体。T1 R2和T1 R3是T1 R I型味觉受体家族的两种相关的G蛋白偶联受体。T1 R2 + T1 R3对所有类型的甜味化合物都有反应。T1 R具有由捕蝇草模块和富含半胱氨酸的结构域组成的大的细胞外结构域、7-跨膜结构域和短的C-末端尾。本申请的主要目标是阐明人类T1 R2 + T1 R3二聚体受体与甜味蛋白莫内林相互作用的结构-功能关系。我将利用莫内林作用于人类甜味受体而不作用于小鼠受体的事实，来鉴定负责人类受体对莫内林反应的特定残基。我们先前对人/小鼠嵌合体的研究表明，人T1 R2（hT 1 R2）的氨基末端结构域（ATD）对于对莫内林的反应至关重要。我们还表明，T1 R3的富含半胱氨酸的结构域（CRD）在莫内林激活受体中起作用。本申请的第一个目的是鉴定T1 R2的ATD内对甜受体对莫内林的敏感性至关重要的残基。为了实现这一目标，1将使用含有人和小鼠T1 R2的不同部分的T1 R2嵌合体，并进行定点诱变。第二个目的是鉴定hT 1 R3的CRD内的残基，其对于甜受体对莫内林的敏感性至关重要。这一目标将通过CRD的定向诱变来实现，所述定向诱变基于我们对该受体区域中对应耐菌素应答至关重要的残基的初步鉴定。T1 R的结构/功能关系的知识可能在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方面具有价值。

DESCRIPTION (provided by applicant): The sweet receptor, composed of the monomers T1R2+T1R3, is the principal receptor responsible for sweet taste in mammals. T1R2 and T1R3 are two related G protein-coupled receptors of the T1R type I taste receptor family. Together, T1R2+T1R3 respond to all classes of sweet compounds. T1Rs have a large extracellular domain consisting of a Venus flytrap module and a cysteine-rich domain, a 7-transmembranes domain, and a short C-terminal tail. The primary goal of this application is to elucidate structure-function relationships underlying human T1R2+T1R3 dimeric receptor interactions with the sweet tasting protein monellin. I will take advantage of the fact that monellin acts on the human sweet receptor, but not on the mouse receptor, to identify the specific residues responsible for the human receptor's response to monellin. Our previous work with human/mouse chimeras has shown that the amino-terminal domain (ATD) of human T1R2 (hT1R2) is critical for the response to monellin. We also have shown that the cysteine-rich domain (CRD) of T1R3 plays a role in monellin's activation of the receptor. The first aim of this application is to identify residues within the ATD of T1R2 critical for sweet receptor sensitivity to monellin. To accomplish this aim 1 will use chimeras of T1R2 containing varying parts of human and mouse T1R2, and carry out site-directed mutagenesis. The second aim is to identify residues within the CRD of hT1R3 critical for sweet receptor sensitivity to monellin. This aim will be accomplished by directed mutagenesis of the CRD based on our initial identification of residues in this region of the receptor that are critical for responses to monellin. Knowledge of the structure/function relationship of T1Rs may be valuable in the development of novel, low caloric sweeteners to help fight against diet-related disorders such as obesity and diabetes.