Variable domains in hagfish:: NICIR is a polymorphic multigene family expressed preferentially in leukocytes and is related to lamprey TCR-like
Variable domains in hagfish:: NICIR is a polymorphic multigene family expressed preferentially in leukocytes and is related to lamprey TCR-like
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DOI：
10.1007/s00251-006-0098-1
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发表时间：
2006-04-01
期刊：
影响因子：
3.2
通讯作者：
Kasahara, M
中科院分区：
文献类型：
--
作者：
Haruta, C;Suzuki, T;Kasahara, M
以七鳃鳗和七鳃鳗为代表的无颌脊椎动物是最高级的动物，显然缺乏T细胞和B细胞受体。因此，它们为了解抗原受体和可变(V)型免疫球蛋白(Ig)样结构域的进化提供了独特的机会。在本研究中，我们描述了四个带有V型结构域的八目鳗Ig超家族(IgSF)成员。它们中没有一个在有颌骨的脊椎动物中有直接的对应物，这表明许多IgSF分子要么在有颌骨的和没有颌骨的脊椎动物中独立进化，要么分歧到无法再识别明显同源性的程度。其中一个成员编码与先前描述的膜蛋白密切相关的分子，命名为包含IgSF受体(NICIR)的新型免疫受体酪氨酸激活基序(ITAM)。我们在这里表明，NICIR是一个至少有三个成员的多态多基因家族，主要在外周血白细胞中表达。系统发育分析表明，在已知的蛋白质中，NICIR与最近被认为是T细胞受体的潜在祖先的七鳃鳗分子关系最为密切。
The jawless vertebrates, represented by hagfish and lampreys, are the most advanced animals that apparently lack T cell and B cell receptors. As such, they offer unique opportunities for understanding the evolution of antigen receptors and variable (V)-type immunoglobulin (Ig)-like domains. In the present study, we describe four hagfish Ig superfamily (IgSF) members carrying V-type domains. None of them appeared to have direct counterparts in jawed vertebrates, indicating that many IgSF molecules have either evolved independently in jawed and jawless vertebrates or diverged to the extent that clear homology is no longer recognizable. One of the members encoded a molecule closely related to the previously described membrane protein designated novel ITAM (immunoreceptor tyrosine-based activation motif)-containing IgSF receptors (NICIR). We show here that NICIR is a polymorphic multigene family with at least three members and is expressed predominantly in peripheral blood leukocytes. Phylogenetic analysis indicates that among known proteins, NICIR is most closely related to the lamprey molecule recently proposed to be a potential ancestor of T cell receptors.