Cloning, expression, and characterization of fugu CD4, the first ectothermic animal CD4
Cloning, expression, and characterization of fugu CD4, the first ectothermic animal CD4
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DOI：
10.1007/s00251-004-0694-x
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发表时间：
2004-07
期刊：
影响因子：
3.2
通讯作者：
H. Suetake;Kyosuke Araki;Yuzuru Suzuki
中科院分区：
文献类型：
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作者：
H. Suetake;Kyosuke Araki;Yuzuru Suzuki
利用公共数据库中的第三份基因组草图序列，我们从红鳍东方鲀中克隆了第一个变温动物CD 4基因，并进行了序列测定。fuguCD 4基因编码一个463个氨基酸的蛋白质，包含4个细胞外免疫球蛋白（IG）样结构域、一个跨膜区和一个胞质尾区。河豚CD 4与禽类和哺乳动物的CD 4蛋白具有约15-20%的低同源性。与鸟类和哺乳动物的CD 4不同，河豚CD 4缺乏第一个Ig样结构域的Cys对，但在第三个结构域中具有独特的可能的二硫键。这些差异表明，河豚CD 4可能具有不同的结构，可能会影响主要组织相容性复合体II类分子的结合和随后的T细胞活化。在推定的河豚鱼胞质区域，蛋白酪氨酸激酶p56 lck结合基序是保守的。预测的fuguCD 4基因由12个外显子组成，与其他CD 4基因不同，但在启动子区显示出保守的同线性和许多保守的序列基序。RT-PCR分析表明fuguCD 4基因主要在淋巴组织中表达。我们还表明，河豚CD 4可以通过转染表达在细胞表面。鱼类中CD 4的分子特征提供了对CD 4分子和免疫系统进化的见解。
We have cloned and sequenced the first ectothermic animalCD4gene from fugu,Takifugu rubripes, using a public database of the third draft sequence of the fugu genome. The fuguCD4gene encodes a predicted protein of 463 amino acids containing four extracellular immunoglobulin (Ig)-like domains, a transmembrane region, and a cytoplasmic tail. Fugu CD4 shares low identity of about 15–20% with avian and mammalian CD4 proteins. Unlike avian and mammalian CD4, fugu CD4 lacks the Cys pair of the first Ig-like domain, but has a unique possible disulfide bond in the third domain. These differences suggest that fugu CD4 may have a different structure that could affect binding of major histocompatibility complex class II molecules and subsequent T-cell activation. In the putative fugu cytoplasmic region, the protein tyrosine kinase p56lckbinding motif is conserved. The predicted fuguCD4gene is composed of 12 exons, differing from otherCD4genes, but showing conserved synteny and many conserved sequence motifs in the promoter region. RT-PCR analysis demonstrated that the fuguCD4gene is expressed predominantly in lymphoid tissues. We also show that fugu CD4 can be expressed on the surface of cells via transfection. Molecular characterization of CD4 in fish provides insights into the evolution of both the CD4 molecule and the immune system.