甜味识别与转导机理

甜味是动物最喜好的基本味感,甜味食物通常能为机体提供所需的碳水化合物。功能学研究表明,甜味是由T1R2和T1R3介导的。它们单独存在时是糖的低亲和力受体;它们以异二聚体存在时,是糖和各种人工甜味剂的高亲和力受体。T1R2和T1R3在甜味感受中发挥着不同的作用。T1R2的N端是某些甜味剂(如阿斯巴甜和莫内林)的重要结合位点,C端跨膜区与G蛋白偶联;T1R3的跨膜区也是某些甜味剂的结合位点,该部位可能在受体的激活过程中发挥着关键作用。甜味受体具有多个结合位点,用以识别结构各异的甜味物质。由于甜味化合物化学构成不同,甜味信息的转导可能存在着不同的路径。

Sweet Perception and Transduction Mechanism

The sweet taste is the basic taste which animal most likes,and sweet food usually can provide the carbohydrate for the organism.The functional researches found that T1R2 and T1R3 are the receptors for sweet taste stimuli.T1R2 and T1R3 may function on their own as low-affinity receptors for natural sugars,while the T1R2 T1R3 heteromeric receptor has much higher affinity for natural sugars and artificial sweeteners.T1R2 and T1R3 have different functional roles in the sweet perception.The N-terminal domain of T1R2 is required for recognizing sweeteners,such as aspartame and neotame.The G protein coupling requires the C-terminal transmembrane domain of T1R2.The transmembrane domain of T1R3 is required for recognizing some sweeteners,such as cylamate,and this site maybe play a critical role in the activation of the sweet receptor.Now,some findings indicate the existence of multiple binding sites on the receptor for different classes of sweeteners.Sweet compounds are extremely diverse in their chemical composition,so there are different sweet signal transduction pathways.