Characterisation of salmon and trout CD8α and CD8β
Characterisation of salmon and trout CD8α and CD8β
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DOI：
10.1016/j.molimm.2004.11.017
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发表时间：
2005-06-01
影响因子：
3.6
通讯作者：
Hordvik, I
中科院分区：
文献类型：
--
作者：
Moore, LJ;Somamoto, T;Hordvik, I
对大西洋鲑鱼(Sallno Salar)CD8分子的α链和β链的基因及其相应的cDNA进行了测序和特征分析。此外，还对褐鲑鱼(Salmo Trutta)的α链和β链以及虹鱼(Oncorhynchus MykISS)的β链进行了测序。CDNAs编码前面有短的5‘UTRs的信号序列。紧随其后的是典型的免疫球蛋白超家族变量序列，它们都包含两个保守的半胱氨酸，用于链内二硫键。铰链区显示了用于二聚的保守半胱氨酸和每个预测蛋白质的几个O-糖基化基序。与哺乳动物具有最高序列同源性的结构域是所有序列的单次通过跨膜结构域。在鲑鱼中，除了细胞质/3‘UTR域之外，每个结构域主要由单个外显子编码，这两个结构域分别由α和β基因的3和2个外显子编码。在阿尔法基因中，第二个细胞质外显子可能被剪接出来，形成一个可供选择的较短的转录本，如果表达，将显示一个截断的细胞质尾巴。鲑鱼贝塔基因的一种剪接变体仅在40个氨基酸之后引入了一个终止密码子。总体而言，鲑鱼的氨基酸序列同源性超过90%，而它们与鸡和人等物种的同源性只有15%-20%。用定量RT-PCR分析这两个三文鱼基因的表达模式表明，这两个基因在胸腺中表达非常高。这反映在TCRα基因的表达上，众所周知，TCRα基因与CD8β在哺乳动物T细胞上共表达。这是硬骨中CD8β序列的首次报道，它与CD8α序列一起编码哺乳动物T细胞上CD8β共受体分子的同源基因。(C)2004爱思唯尔有限公司。保留所有权利。
The genes and corresponding cDNAs of both alpha and beta chains of the Atlantic salmon (Sallno salar) CD8 molecule have been sequenced and characterized. In addition, the cDNAs for alpha and beta chains of brown trout (Salmo trutta) and for the beta chain in rainbow trout (Oncorhynchus mykiss) have been sequenced. The cDNAs code for signal sequences which are preceded by short 5' UTRs. These are followed by typical immunoglobulin superfamily variable sequences all of which contain two conserved cysteines for the intra-chain disulphide bond. The hinge regions display conserved cysteines for dimerisation and several O-glycosylation motifs for each predicted protein. The domain sharing the highest sequence identity with mammals is the single pass transmembrane domain for all sequences. In salmon, each domain is predominantly coded for by a single exon except the cytoplasmic/3' UTR domains, which are coded for by 3 and 2 exons for the alpha and beta genes, respectively. In the alpha gene, the second cytoplasmic exon may be spliced out to form an alternative shorter transcript which if expressed would exhibit a truncated cytoplasmic tail. A splice variant found for the salmon beta gene introduces a stop codon after only 40 amino acids. Overall amino acid identities between salmonid sequences were higher than 90 %, whereas they shared only 15-20 % identity with species such as, chicken and human. Analysis of the expression patterns of the two salmon genes using quantitative RT-PCR shows a very high expression in the thymus. This is mirrored by the expression of the TCR alpha gene, which is known to be co-expressed with CD8 beta on mammalian T cells. This is the first report of a sequence for CD8 beta in a teleost and together with the CD8 alpha sequence, it encodes the ortholog of the CD8 beta co-receptor molecule on mammalian T cells. (c) 2004 Elsevier Ltd. All rights reserved.