cDNA cloning and primary structure analysis of invariant chain in Chinese Pengze crucian carp
cDNA cloning and primary structure analysis of invariant chain in Chinese Pengze crucian carp
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DOI：
10.5897/ajb11.871
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发表时间：
2011-08
影响因子：
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通讯作者：
Xuelan Liu;Weiyi Yu;Jinnian Li;Fangfang Chen;Shengjie Liu;Chao Wu;Jia‐Ping Xu
中科院分区：
文献类型：
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作者：
Xuelan Liu;Weiyi Yu;Jinnian Li;Fangfang Chen;Shengjie Liu;Chao Wu;Jia‐Ping Xu
不变量链（Ii）在脊椎动物MHC Ii类分子组装和外源肽呈递中起重要作用。尽管哺乳动物Ii已被广泛研究，但对鱼类Ii的关注较少。本研究为了解中国彭泽鲫（Carassius auratus） Ii的结构和生物学功能，首先利用RT - PCR和cDNA末端快速扩增技术克隆了Ii基因（Caau-Ii）。首先，利用鱼头部、肾脏和脾脏总RNA的一对简并引物扩增出保守的DNA片段。然后设计RACE特异性引物扩增Caau-Ii的5′和3′端。最后，对Caau-Ii全长cDNA进行扩增、测序和分析，结果表明该cDNA全长1063 bp，包含一个696 bp的开放阅读框，编码Caau-Ii前体蛋白。氨基酸序列比对结果表明：(1)Caau-Ii与鲤鱼、斑马鱼同源性高（70%），与哺乳动物同源性低（30% <40%）；(2) Caau-Ii具有与哺乳动物Ii相似的结构域，包括跨膜结构域、Ii类相关Ii衍生肽（CLIP）和TRIM（三聚化）结构域。关键词：不变量链，鲫鱼，RACE，克隆，结构域分析
Invariant chain (Ii) plays an important role in MHC class II molecules assembly and exogenous peptide presentation in vertebrates. Although mammalian Ii has been extensively studied, less attention is paid to its fish counterpart. In this study, in order to understand the structure and biological function of Chinese Pengze crucian carp ( Carassius auratus) Ii, we first cloned Ii gene ( Caau-Ii ) using RT PCR and rapid amplification of cDNA end techniques. Firstly, a conserved DNA fragment was amplified using a pair of degenerate primers from fish’s head kidney and spleen total RNA. Then specific primers for RACE were designed to amplify the 5' and 3' ends of Caau-Ii . Finally, the full-length cDNA of Caau-Ii was amplified, sequenced and analyzed and the results showed that it was 1063 bp in length and contained an open reading frame of 696 bp encoding Caau-Ii precursor protein. Amino acid sequence alignment showed that (1) Caau-Ii had high homology with that of carp and zebrafish (identify >70%) and low homology with mammalian Ii (30% < identity <40%); (2) Caau-Ii had similar domains seen in mammalian Ii, including transmembrane domain, CLIP (class II-associated Ii-derived peptide) and TRIM (trimerization) domain. Key words: Invariant chain, Carassius auratus, RACE, cloning, domain analysis.