He Yiduo, Xi Dongmei, Leng Jing, Qian Tao, Jin Dan, Chen Ting, Yang Chunling, Hao Tiantian, Yang Zaiqing, Deng Weidong
Faculty of Animal Science and Technology, Yunnan Agricultural University, Kunming, 650201, People's Republic of China.
Mol Biol Rep. 2014;41(4):2199-206. doi: 10.1007/s11033-014-3071-3. Epub 2014 Jan 16.
The major histocompatibility class (MHC) DQ molecules are dimeric glycoproteins revealing antigen presentation to CD(4+) T cells. In the present study, the exon 2 of the MHC class II DQB gene from 32 yaks (Bos grunniens) was cloned, sequenced and compared with previously reported patterns for other bovidae. It was revealed by sequence analyses that there are 25 DQB exon 2 alleles among 32 yaks, all alleles are found to belong to DQB1 loci. These alleles exhibited a high degree of nucleotide and amino acid polymorphisms with most amino acid variations occurring at positions forming the peptide-binding sites. The DQB loci were analyzed for patterns of synonymous (d S) and non-synonymous (d N) substitution. The yak was observed to be under strong positive selection in the DQB exon 2 peptide-binding sites (d N = 0.15, P < 0.001). It appears that this variability among yaks confers the ability to mount immune responses to a wide variety of peptides or pathogens.
主要组织相容性复合体（MHC）DQ分子是一种二聚体糖蛋白，可将抗原呈递给CD4+T细胞。在本研究中，克隆并测序了32头牦牛（Bos grunniens）MHC II类DQB基因的外显子2，并与先前报道的其他牛科动物的模式进行了比较。序列分析显示，32头牦牛中有25个DQB外显子2等位基因，所有等位基因均属于DQB1位点。这些等位基因表现出高度的核苷酸和氨基酸多态性，大多数氨基酸变异发生在形成肽结合位点的位置。分析了DQB位点的同义替换（dS）和非同义替换（dN）模式。在牦牛DQB外显子2肽结合位点观察到强烈的正选择（dN = 0.15，P < 0.001）。牦牛之间的这种变异性似乎赋予了它们对多种肽或病原体产生免疫反应的能力。
