Molecular cloning of a lamprey homologue of the mammalian MHC class III gene, complement factor B.
Molecular cloning of a lamprey homologue of the mammalian MHC class III gene, complement factor B.
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DOI：
10.4049/jimmunol.152.5.2263
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发表时间：
1994-03
影响因子：
4.4
通讯作者：
M. Nonaka;M. Takahashi;M. Sasaki
中科院分区：
文献类型：
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作者：
M. Nonaka;M. Takahashi;M. Sasaki
为了阐明补体系统和MHC的起源和进化，我们从七鳃鳗（最原始的现存脊椎动物之一）中分离了MHC III类补体因子B（Bf）基因的cDNA克隆。利用与小鼠Bf和C2序列之间保守氨基酸序列相对应的简并引物，通过逆转录-PCR扩增七鳃鳗Bf的丝氨酸蛋白酶结构域的一部分。用PCR扩增的DNA克隆作为探针，从七鳃鳗肝脏cDNA文库中分离出全长七鳃鳗Bf cDNA克隆。推导的763个残基的氨基酸序列显示出与哺乳动物Bf或C2基本相同的结构域结构，由三个短的一致重复结构域、一个von Willebrand结构域和一个丝氨酸蛋白酶结构域组成。七鳃鳗Bf与小鼠Bf和小鼠C2的氨基酸相似性分别为33%和29%，而小鼠Bf与小鼠C2的氨基酸相似性为36%，表明Bf/C2的基因重复发生在圆口动物分化后的脊椎动物进化主线上。这是第一次报告的分子克隆从圆口动物的一个组成部分的哺乳动物的MHC，提供了可能性的遗传分析的推测原始MHC的圆口动物。
To elucidate the origin and evolution of the complement system and the MHC, we isolated cDNA clones for the MHC class III complement factor B (Bf) gene from lamprey, one of the most primitive extant vertebrates. A part of the serine protease domain of the lamprey Bf was amplified by reverse transcriptase-PCR using the degenerated primers corresponding to the conserved amino acid stretches between the mouse Bf and C2 sequences. A full-length lamprey Bf cDNA clone was isolated from the lamprey liver cDNA library using a PCR-amplified DNA clone as a probe. The deduced amino acid sequence of 763 residues showed essentially the same domain structure as mammalian Bf or C2, consisting of three short consensus repeat domains, a von Willebrand domain, and a serine protease domain. Lamprey Bf showed 33 and 29% overall amino acid similarity to mouse Bf and mouse C2, respectively, whereas amino acid similarity between mouse Bf and mouse C2 was 36%, suggesting that the gene duplication of Bf/C2 occurred in the main line of vertebrate evolution after the divergence of cyclostomes. This is the first report of the molecular cloning from cyclostomes of a component of the mammalian MHC that offers the possibility of genetic analysis of the presumably primitive MHC of cyclostomes.