Kitano T, Saitou N
Laboratory of Evolutionary Genetics, National Institute of Genetics, Mishima, Japan.
Immunogenetics. 2000 Aug;51(10):856-62. doi: 10.1007/s002510000202.
Rh and its homologous Rh50 gene products are considered to form heterotetramers on erythrocyte membranes. Rh protein has Rh blood group antigen sites, while Rh50 protein does not, and is more conserved than Rh protein. We previously determined both Rh and Rh50 gene cDNA coding regions from mouse and rat, and carried out phylogenetic analyses. In this study, we determined Rh50 gene cDNA coding regions from African clawed frog and Japanese medaka fish, and examined the long-term evolution of the Rh blood group and related genes. We constructed the phylogenetic tree from amino acid sequences. Rh50 genes of African clawed frog and Japanese medaka fish formed a cluster with mammalian Rh50 genes. The gene duplication time between Rh and Rh50 genes was estimated to be about 510 million years ago based on this tree. This period roughly corresponds to the Cambrian, before the divergence between jawless fish and jawed vertebrates. We also BLAST-searched an amino acid sequence database, and the Rh blood group and related genes were found to have homology with ammonium transporter genes of many organisms. Ammonium transporter genes can be classified into two major groups (amt alpha and amt beta). Both groups contain genes from three domains (bacteria, archaea, and eukaryota). The Rh blood group and related genes are separated from both amt alpha and beta groups.
Rh及其同源的Rh50基因产物被认为在红细胞膜上形成异源四聚体。Rh蛋白具有Rh血型抗原位点，而Rh50蛋白没有，并且比Rh蛋白更保守。我们之前已确定了小鼠和大鼠的Rh及Rh50基因cDNA编码区，并进行了系统发育分析。在本研究中，我们确定了非洲爪蟾和日本青鳉的Rh50基因cDNA编码区，并研究了Rh血型及相关基因的长期进化。我们根据氨基酸序列构建了系统发育树。非洲爪蟾和日本青鳉的Rh50基因与哺乳动物的Rh50基因形成一个聚类。基于此树，Rh和Rh50基因之间的基因复制时间估计约为5.1亿年前。这一时期大致对应寒武纪，早于无颌鱼类和有颌脊椎动物的分化。我们还对氨基酸序列数据库进行了BLAST搜索，发现Rh血型及相关基因与许多生物体的铵转运蛋白基因具有同源性。铵转运蛋白基因可分为两个主要组（amtα和amtβ）。这两个组都包含来自三个域（细菌、古细菌和真核生物）的基因。Rh血型及相关基因与amtα和β组均分离。
