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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Primitive synteny of vertebrate major histocompatibility complex class Ⅰ and class Ⅱ genes
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Primitive synteny of vertebrate major histocompatibility complex class Ⅰ and class Ⅱ genes

机译：脊椎动物主要组织相容性复合体Ⅰ类和Ⅱ类基因的原始同构

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摘要

Major histocompatibility complex (MHC) class Ⅰand class Ⅱ mole- cules bind to and display peptidic antigens acquired from patho- gens that are recognized by lymphocytes coordinating and executing adaptive immune responses. The two classes of MHC proteins have nearly identical tertiary structures and were derived from a common ancestor that probably existed not long before the emergence of the cartilaginous fish. Class Ⅰand class Ⅱ genes are genetically linked in tetrapods but are not syntenic in teleost fish, a phylogenetic taxon derived from the oldest vertebrate ancestor examined to date. Cartilaginous fish (sharks, skates, and rays) are in the oldest taxon of extant jawed vertebrates; we have carried out segregation analyses in two families of nurse sharks and one family of the banded houndshark that revealed a close linkage of class Ⅱα and β genes both with each other and with the classical class Ⅰ(class Ⅰα) gene. These results strongly suggest that the primordial duplication giving rise to classical class Ⅰand class Ⅱ occurred in cis, and the close linkage between these two classes of genes has been maintained for at least 460 million years in representatives of most vertebrate taxa.
机译：主要的组织相容性复合体（MHC）Ⅰ类和Ⅱ类分子与从病原体获得的肽抗原结合并显示出肽抗原，这些抗原被淋巴细胞识别并协调并执行适应性免疫应答。这两类MHC蛋白具有几乎相同的三级结构，并源自可能在软骨鱼出现前不久就存在的共同祖先。 Ⅰ类和Ⅱ类基因在四足动物中有遗传联系，但在硬骨鱼类中是非同系的，硬骨鱼类是迄今为止研究的最古老的脊椎动物祖先衍生的系统发育分类群。软骨鱼类（鲨鱼，溜冰鞋和rays鱼）在现存的有颚脊椎动物中是最古老的分类群。我们在两个鲨鱼科和一个带状猎犬中进行了分离分析，结果表明，Ⅱα和β类基因彼此之间以及与经典Ⅰ类（Ⅰα类）基因之间都存在着紧密的联系。这些结果强烈表明，引起经典Ⅰ类和Ⅱ类的原始复制发生在顺式中，并且在大多数脊椎动物类群的代表中，这两类基因之间的紧密联系至少维持了4.6亿年。

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