Nucleotide sequence and the molecular evolution of a new A2 gene in the DQ subregion of the bovine major histocompatibility complex.
Nucleotide sequence and the molecular evolution of a new A2 gene in the DQ subregion of the bovine major histocompatibility complex.
复制标题
牛主要组织相容性复合体 DQ 亚区新 A2 基因的核苷酸序列和分子进化。
DOI：
10.1006/bbrc.1995.1943
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发表时间：
1995
影响因子：
3.1
通讯作者：
Y. Aida
中科院分区：
文献类型：
--
作者：
A. Morooka;M. Asahina;C. Kohda;S. Tajima;M. Niimi;Y. Nishino;M. Sugiyama;Y. Aida
分离了编码牛主要组织相容性复合体(MHC)II类DQα链的cDNA克隆。其中一个克隆MQ9编码255个氨基酸的初级翻译产物，23个氨基酸的信号肽和232个氨基酸的成熟多肽。通过对几个物种的II类A基因编码的氨基酸序列的比较和系统发育树的构建，在牛基因组DQ亚区发现了一个新的A2基因。在各种哺乳动物的序列中，MQ9与绵羊DQA2基因的亲缘关系最近。相比之下，之前分离的BOLA-DQA基因与绵羊DQA1的亲缘关系比与BOLA-DQA2基因的亲缘关系更近，它们代表了BOLA-DQA1基因。因此，证实了两个BOLA A基因的存在，这两个基因可能在牛和绵羊中表达并具有功能。比较了牛和羊源DQA2基因产物的氨基酸序列，发现了这两个物种所特有的大量氨基酸，大部分DQA2特异残基位于α1区，与反刍动物的DQA1基因产物相比较保守。因此，牛的DQA基因的一些特征被发现与人类和啮齿动物的基因不同，尽管在基因结构和核苷酸序列上相似。
cDNA clones encoding the bovine major histocompatibility complex (MHC) class II DQ alpha chain were isolated. One clone, MQ9, encoded a primary translated product of 255 amino acids, with a signal peptide of 23 amino acids and a mature polypeptide of 232 amino acids. A new A2 gene in the DQ subregion of the bovine genome was identified from a comparison of amino acid sequences encoded by class II A genes among several species and the construction of a phylogenetic tree. It was revealed that MQ9 is most closely related to the ovine DQA2 genes among sequences from various mammalian species. By contrast, the BoLA-DQA genes previously isolated are more closely related to ovine DQA1 than to the BoLA-DQA2 gene, and they represent BoLA-DQA1 genes. Thus, the presence of two BoLA A genes, which may be expressed and functional in the bovine, as well as in sheep was confirmed. A large number of amino acids unique to products of DQA2 genes of bovine and ovine origin were identified when the predicted amino acid sequences for both species were compared, and most of the DQA2-specific residues were located in the alpha 1 domain and were conserved with respect to products of DQA1 genes of ruminants. Thus, several characteristics of the bovine DQA genes were found to differ from those of human and rodent genes, despite similarities in gene structure and in nucleotide sequence.