Cloning and characterization of human NTT5 and v7-3:: Two orphan transporters of the Na+/Cl--dependent neurotransmitter transporter gene family
Cloning and characterization of human NTT5 and v7-3:: Two orphan transporters of the Na+/Cl--dependent neurotransmitter transporter gene family
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DOI：
10.1006/geno.2000.6387
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发表时间：
2000-12-01
期刊：
影响因子：
4.4
通讯作者：
Pangalos, MN
中科院分区：
文献类型：
--
作者：
Farmer, MK;Robbins, MJ;Pangalos, MN
孤儿转运蛋白形成了一个不断增长的基因亚家族，通过序列相似性与Na+/Cl(-)依赖的神经递质超家族相关。采用数据库相似性搜索和克隆相结合的方法，我们已经鉴定并鉴定了两个新的人类孤儿转运蛋白基因v7-3和NTT5。与其他已知的孤儿转运蛋白一样，v7-3和NTT5包含12个预测的跨膜结构域，细胞内的N-末端和C-末端结构域，以及跨膜(TM)结构域3和4之间以及Tri结构域7和8之间的大型胞外环。胞外环内的残基也被预测包含N连接的糖基化位点。人v7-3是大鼠v7-3的同源基因，含有730个氨基酸的开放阅读框架(ORF)。人NTT5是孤儿转运蛋白家族的新成员，其开放阅读框架由736个氨基酸组成。人的v7-3和NTT5的氨基酸序列与其他已知的孤儿神经递质转运蛋白的相似性超过50%，也与人的5-羟色胺和多巴胺转运蛋白的序列相似。辐射杂交定位人v7-3和NTT5基因分别位于染色体12q21.3-q21.4和19q13.1-q13.4。TaqMan逆转录-聚合酶链式反应分析表明，v7-3mRNA主要在神经元组织中表达，特别是杏仁核、壳核和胼胝体，在周围组织中表达水平较低。相反，NTT5mRNA在外周组织中高表达，特别是在睾丸、胰腺和前列腺中。用带有表位标记的转运体构建的瞬时转染显示v7-3在细胞表面表达，而NTT5主要在细胞内表达，提示存在囊泡位置。尽管这些转运蛋白运输的底物仍不清楚，但它们具体但广泛的分布表明，它们可能在大脑和外周调节不同和重要的功能。(C)2000年学术出版社。
Orphan transporters form a growing subfamily of genes related by sequence similarity to the Na+/Cl(-)dependent neurotransmitter superfamily. Using a combination of database similarity searching and cloning methods, we have identified and characterized two novel human orphan transporter genes, v7-3 and NTT5. Similar to other known orphan transporters, v7-3 and NTT5 contain 12 predicted transmembrane domains, intracellular N- and C-terminal domains, and large extracellular loops between transmembrane (TM) domains 3 and 4 and between TRI domains 7 and 8. Residues within the extracellular loops are also predicted to contain sites for N-linked glycosylation. Human v7-3, the species orthologue of rat v7-3, contains an open reading frame (ORF) of 730 amino acids. Human NTT5 is a new member of the orphan transporter family and has an ORF of 736 amino acids. The amino acid sequences of human v7-3 and NTT5 are greater than 50% similar to other known orphan neurotransmitter transporters and also show sequence similarity to the human serotonin and dopamine transporters. Radiation hybrid mapping located the human v7-3 and NTT5 genes on chromosomes 12q21.3-q21.4 and 19q13.1-q13.4, respectively. Human mRNA distribution analysis by TaqMan reverse transcription-polymerase chain reaction showed that v7-3 mRNA is predominantly expressed in neuronal tissues, particularly amygdala, putamen, and corpus callosum, with low-level expression in peripheral tissues. In contrast, NTT5 mRNA was highly expressed in peripheral tissues, particularly in testis, pancreas, and prostate. Transient transfection with epitope-tagged transporter constructs demonstrated v7-3 to be expressed at the cell surface, whereas NTT5 was predominantly intracellular, suggestive of a vesicular location. Although the substrates transported by these transporters remain unknown, their specific but widespread distribution suggests that they may mediate distinct and important functions within the brain and the periphery. (C) 2000 Academic Press.