In contrast to carbohydrates and proteins, which are detected by specialized taste receptors in the forms of their respective building blocks, sugars, and L-amino acids, the third macronutrient, lipids, has until now not been associated with gustatory receptors. Instead, the recognition of fat stimuli was believed to rely mostly on textural, olfactory, and postingestive cues. During the recent years, however, research done mainly in rodent models revealed an additional gustatory component for the detection of long-chain fatty acids (LCFAs), the main taste-activating component of lipids. Concomitantly, a number of candidate fat taste receptors were proposed to be involved in rodent's gustatory fatty acid perception. Compared with rodent models, much less is known about human fat taste. In order to investigate the ability of the human gustatory system to respond to fat components, we performed sensory experiments with fatty acids of different chain lengths and derivatives thereof. We found that our panelists discriminated a "fatty" and an irritant "scratchy" taste component, with the "fatty" percept restricted to LCFAs. Using functional calcium-imaging experiments with the human orthologs of mouse candidate fat receptors belonging to the G protein-coupled receptor family, we correlated human sensory data with receptor properties characterized in vitro. We demonstrated that the pharmacological activation profile of human GPR40 and GPR120, 2 LCFA-specific receptors associated with gustatory fat perception in rodents, is inconsistent with the "scratchy" sensation of human subjects and more consistent with the percept described as "fatty." Expression analysis of GPR40 and GPR120 in human gustatory tissues revealed that, while the GPR40 gene is not expressed, GPR120 is detected in gustatory and nongustatory epithelia. On a cellular level, we found GPR120 mRNA and protein in taste buds as well as in the surrounding epithelial cells. We conclude that GPR120 may indeed participate in human gustatory fatty acid perception.

中文翻译：

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人体脂肪味觉感知中的G蛋白偶联受体。

与专门的味觉受体以其各自的结构单元，糖和L-氨基酸的形式检测到的碳水化合物和碳水化合物相反，第三种常量营养元素脂质迄今尚未与味觉受体相关。相反，人们认为脂肪刺激的识别主要依赖于质地，嗅觉和张贴性暗示。但是，近年来，主要在啮齿动物模型中进行的研究揭示了用于检测长链脂肪酸（LCFA）的另一种味觉成分，LCFA是脂质的主要味道激活成分。同时，提出了许多候选脂肪味觉受体与啮齿动物的味觉脂肪酸感知有关。与啮齿动物模型相比，人们对脂肪的了解还很少。为了研究人类味觉系统对脂肪成分的反应能力，我们对不同链长的脂肪酸及其衍生物进行了感官实验。我们发现，我们的小组成员区分了“脂肪”和刺激性“抓痒”味道成分，其中“脂肪”感知仅限于LCFA。使用功能性钙成像实验与属于G蛋白偶联受体家族的小鼠候选脂肪受体的人类直系同源基因，我们将人类感觉数据与体外表征的受体特性相关联。我们证明了人类GPR40和GPR120（与啮齿类动物的味觉脂肪相关的2种LCFA特异性受体）的药理激活特性与“抓痒”不一致 人体的感觉与被描述为“脂肪”的感觉更为一致。GPR40和GPR120在人味觉组织中的表达分析表明，虽然GPR40基因未表达，但在味觉和非味觉上皮中均检测到GPR120。在细胞水平上，我们在味蕾以及周围的上皮细胞中发现了GPR120 mRNA和蛋白质。我们得出结论，GPR120确实可能参与了人类味觉脂肪酸的感知。