Two families of candidate taste receptors in fishes
Two families of candidate taste receptors in fishes
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DOI：
10.1016/j.mod.2005.07.005
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发表时间：
2005-12-01
影响因子：
2.6
通讯作者：
Abe, K
中科院分区：
文献类型：
--
作者：
Ishimaru, Y;Okada, S;Abe, K
脊椎动物通过上皮组织中的味蕾细胞接受糖、氨基酸和核苷酸等味觉物质。在哺乳动物中，味蕾细胞中表达了两个G蛋白偶联受体家族——甜味和鲜味（L -氨基酸）的t1rs和苦味的T2Rs。在这里，我们报道了鱼类中两个候选味觉受体家族，鱼类的T1Rs和T2Rs，它们分别与哺乳动物的T1Rs和T2Rs具有显著的相似性。鱼类的t1r由三种类型组成：鱼类的T1R1和T1R3分别与哺乳动物的T1R1和T1R3具有最高的同一性；鱼类的TIR2与哺乳动物的T1R1和TIR2具有几乎相同的同一性。与哺乳动物的T1R2不同，鱼类的TIR2在每个物种中由两到三个成员组成。在原位杂交实验中，我们还发现了两种鱼类的T1R和T2R基因在味蕾细胞中特异性表达，而在嗅觉受体细胞中不表达。鱼类T1R1和TIR2基因在不同的味蕾细胞亚群中表达，鱼类T1R3基因与鱼类T1R1或TIR2基因共表达，与哺乳动物一样。也有相当数量的细胞只表达鱼的TIR2基因。鱼T2R基因在不同细胞中表达，不同细胞表达鱼T1R基因。这些结果表明，脊椎动物通常有两种味觉信号通路，由味觉受体细胞中表达的味觉受体类型决定。2005爱思唯尔爱尔兰有限公司版权所有。
Vertebrates receive tastants, such as sugars, amino acids, and nucleotides, via taste bud cells in epithelia] tissues. In mammals, two families of G protein-coupled receptors for tastants are expressed in taste bud cells-T1Rs for sweet tastants and umami tastants ((L)-amino acids) and T2Rs for bitter tastants. Here, we report two families of candidate taste receptors in fish species, fish T1Rs and T2Rs, which show significant identity to mammalian T1Rs and T2Rs, respectively. Fish T1Rs consist of three types: fish T1R1 and T1R3 that show the highest degrees of identity to mammalian T1R1 and T1R3, respectively, and fish TIR2 that shows almost equivalent identity to both mammalian T1R1 and TIR2. Unlike mammalian T1R2, fish TIR2 consists of two or three members in each species. We also identified two fish T2Rs that show low degrees of identity to mammalian Ms. In situ hybridization experiments revealed that fish T1R and T2R genes were expressed specifically in taste bud cells, but not in olfactory receptor cells. Fish T1R1 and TIR2 genes were expressed in different subsets of taste bud cells, and fish T1R3 gene was co-expressed with either fish T1R1 or TIR2 gene as in the case of mammals. There were also a significant number of cells expressing fish TIR2 genes only. Fish T2R genes were expressed in different cells from those expressing fish T1R genes. These results suggest that vertebrates commonly have two kinds of taste signaling pathways that are defined by the types of taste receptors expressed in taste receptor cells. (c) 2005 Elsevier Ireland Ltd. All rights reserved.