AT LEAST 4 MHC CLASS-I GENES ARE TRANSCRIBED IN THE HORSE - PHYLOGENETIC ANALYSIS SUGGESTS AN UNUSUAL EVOLUTIONARY HISTORY FOR THE MHC IN THIS SPECIES
AT LEAST 4 MHC CLASS-I GENES ARE TRANSCRIBED IN THE HORSE - PHYLOGENETIC ANALYSIS SUGGESTS AN UNUSUAL EVOLUTIONARY HISTORY FOR THE MHC IN THIS SPECIES
复制标题
DOI：
10.1111/j.1744-313x.1995.tb00239.x
复制
发表时间：
1995-06-01
期刊：
影响因子：
--
通讯作者：
MORRISON, WI
中科院分区：
文献类型：
--
作者：
ELLIS, SA;MARTIN, AJ;MORRISON, WI
先前已在单个基因座 (ELA-A) 上通过血清学鉴定了 19 个马 MHC I 类特异性，并且其他基因座似乎编码了另外两个特异性。生化研究表明至少有两个表达位点。为了确定转录的马 MHC I 类基因的数量，我们从杂合动物 (ELA-A3/A7) 中构建了 cDNA 文库，并使用牛 I 类探针筛选阳性克隆。通过这种方式分离出 200 多个 I 类克隆，迄今为止已鉴定出 7 个独特的全长序列。所有序列预计都会编码表面表达的功能分子。鉴定出的不同序列的数量表明至少有四个基因被转录，尽管跨膜长度的变化（通常在I类基因座中保守）表明可以代表五个基因。这些序列（以及已知代表不同马 I 类基因座的两个附加序列）的进化分析表明没有牢固的关系，因此无法辨别不同基因座之间的划分。这些结果表明马 MHC 具有不寻常的进化历史，其确切性质只有在进一步的跨物种比较后才能揭示。
Nineteen horse MHC class I specificities have been serologically identified previously at a single locus (ELA-A), and two other specificities appear to be coded at other loci. Biochemical studies indicate that there are at least two expressed loci. In order to establish the number of transcribed horse MHC class I genes, we made a cDNA library from a heterozygous animal (ELA-A3/A7), and screened for positive clones using a bovine class I probe. More than 200 class I clones were isolated in this way, and so far seven unique full length sequences have been identified. Ail of the sequences are predicted to code for surface expressed, functional molecules. The number of different sequences identified demonstrate that at least four genes are transcribed, although variations in transmembrane length (which is generally conserved in class I loci) suggest that five genes could be represented. Evolutionary analysis of these sequences (and two additional sequences known to represent different horse class I loci) reveals no firm relationships, such that the division between the different loci cannot be discerned. These results suggest an unusual evolutionary history for the horse MHC, the precise nature of which may be revealed only following further cross-species comparisons.