Xenopus class II A genes:: studies of genetics, polymorphism, and expression
Xenopus class II A genes:: studies of genetics, polymorphism, and expression
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DOI：
10.1016/s0145-305x(02)00034-4
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发表时间：
2002-10-01
影响因子：
2.9
通讯作者：
Flajnik, MF
中科院分区：
文献类型：
--
作者：
Liu, Y;Kasahara, M;Flajnik, MF
两栖动物非洲爪蟾是研究主要组织相容性复合体（MHC）进化的重要模型。许多哺乳动物MHC基因的对应物已经在非洲爪蟾中被鉴定，促进了对MHC结构和功能的理解。在这里，我们描述X。绵羊MHC II类α链基因。在四个常用的部分近交系中有三个相关的IIA类基因/单倍型，它们都与功能性MHC连锁。这些基因中至少有两个在f单倍型编码全长cDNA克隆和编码免疫球蛋白样结构域的第三个基因的基因组片段也进行了表征。从两个f/f cDNA克隆推导的蛋白质结构和结构域组织类似于哺乳动物MHC II类-α链。II A类基因的表达在脾和肠中最高，类似于先前检查的II B类基因的组织分布。这两个高表达基因在等位基因之间显示出高序列多样性，与大多数其他物种中发现的相似。令人惊讶的是，II A类等位基因/同种型的转录本大小是不同的，这表明爪蟾II类等位基因谱系是非常古老的。(C)2002爱思唯尔科技有限公司版权所有。
The amphibian Xenopus laevis has been a central model for the study of evolution of the major histocompatibility complex (MHC). Many of the counterparts of mammalian MHC genes have been identified in Xenopus, facilitating the understanding of MHC structure and function. Herein we characterize X. laevis MHC class II-alpha chain genes. There are three related class II A genes/haplotype in the four commonly used partially inbred strains, all of which linked to the functional MHC. At least two of these genes in the f haplotype encode full-length cDNA clones and a genomic fragment encoding the immunoglobulin-like domain of the third gene was also characterized. The protein structure and domain organization deduced from the two f/f cDNA clones are similar to mammalian MHC class II-alpha chains. Expression of class II A genes is highest in the spleen and intestine, similar to the previously examined tissue distribution of class II B genes. The two highly expressed genes display high sequence diversity among alleles, similar to what has been found in most other species. Surprisingly, transcript sizes of class II A alleles/isotypes are diverse, suggesting that Xenopus class II allelic lineages are very old. (C) 2002 Elsevier Science Ltd. All rights reserved.