Department of Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, Nuthetal, Germany.
PLoS One. 2012;7(7):e40304. doi: 10.1371/journal.pone.0040304. Epub 2012 Jul 6.
The sense of taste plays an important role in the evaluation of the nutrient composition of consumed food. Bitter taste in particular is believed to serve a warning function against the ingestion of poisonous substances. In the past years enormous progress was made in the characterization of bitter taste receptors, including their gene expression patterns, pharmacological features and presumed physiological roles in gustatory as well as in non-gustatory tissues. However, due to a lack in TAS2R-specifc antibodies the localization of receptor proteins within gustatory tissues has never been analyzed. In the present study we have screened a panel of commercially available antisera raised against human bitter taste receptors by immunocytochemical experiments. One of these antisera was found to be highly specific for the human bitter taste receptor TAS2R38. We further demonstrate that this antibody is able to detect heterologously expressed TAS2R38 protein on Western blots. The antiserum is, however, not able to interfere significantly with TAS2R38 function in cell based calcium imaging analyses. Most importantly, we were able to demonstrate the presence of TAS2R38 protein in human gustatory papillae. Using double immunofluorescence we show that TAS2R38-positive cells form a subpopulation of PLCbeta2 expressing cells. On a subcellular level the localization of this bitter taste receptor is neither restricted to the cell surface nor particularly enriched at the level of the microvilli protruding into the pore region of the taste buds, but rather evenly distributed over the entire cell body.
味觉在评价所摄入食物的营养成分方面起着重要作用。特别是苦味，被认为是一种对摄入有毒物质的警告功能。在过去的几年中，人们在苦味受体的特征描述方面取得了巨大进展，包括它们的基因表达模式、药理学特征以及在味觉和非味觉组织中的假定生理作用。然而，由于缺乏 TAS2R 特异性抗体，受体蛋白在味觉组织中的定位从未被分析过。在本研究中，我们通过免疫细胞化学实验筛选了一组针对人类苦味受体的商业可得抗血清。其中一种抗血清被发现对人类苦味受体 TAS2R38 具有高度特异性。我们进一步证明，该抗体能够在 Western blot 上检测到异源表达的 TAS2R38 蛋白。然而，该抗血清不能在基于细胞的钙成像分析中显著干扰 TAS2R38 的功能。最重要的是，我们能够证明 TAS2R38 蛋白存在于人类味觉乳头中。通过双重免疫荧光，我们表明 TAS2R38 阳性细胞形成 PLCβ2 表达细胞的亚群。在亚细胞水平上，这种苦味受体的定位既不限于细胞表面，也不在味蕾突出进入味觉感受器孔区的微绒毛水平上特别富集，而是均匀分布在整个细胞体上。
