EVOLUTION OF NOVEL NON CLASSICAL MHC CLASS I GENE IN OLD WORLD PRIMATES

目的评价MHC-E基因座的保守性 在整个类人灵长类动物进化过程中，我们确定了同源物 在六个不同的新大陆猴子物种中发现了人类白细胞抗原-E基因。结果 四种无亲缘关系棉条MHC-E基因的全长序列分析 罗望子素(Saguinus Oedipus)没有显示出多态的证据。 采用聚合酶链式反应、变性梯度凝胶电泳法和直接 测序，我们还在其他五个新大陆发现了MHC-E等位基因 猴子物种，代表所有现存的白颈鹿家族。在……里面 与所有其他经典和非经典MHC I类基因相比， 灵长类的同义核苷酸替换率很高 大于内部非同义核苷酸替换的比率 编码MHC-E的多肽结合区(PBR)的外显子2和3 基因。讨论MHC-E分子的PBR是在 净化选择性压力，以及非常不寻常的进化 这一古老基因的历史进一步证明了 人类白细胞抗原-E基因座的产物具有重要的免疫功能。 鉴于PBR在以下方面的显著保存，未来方向 灵长类进化，这一关键的免疫功能可能是 与MHC-E蛋白的多肽结合能力有关。钥匙 Words MHC，HLA-E，New World Funding NIH RR00167，DK44886出版物 Knapp，洛杉矶，Cadavid，LF和D.I.Watkins1998年。MHC-E基因座是 在所有已知的灵长类动物中，最古老和保存最完好的一类 组织相容性基因。J.免疫。160：189-196。

OBJECTIVE To evaluate the conservation of the MHC-E locus throughout anthropoid primate evolution, we identified the homologue of the HLA-E locus in six different New World monkey species. RESULTS Full-length sequencing of MHC-E cDNAs in four unrelated cotton-top tamarins (Saguinus oedipus) revealed no evidence for polymorphism. Using the PCR, denaturing gradient gel electrophoresis, and direct sequencing, we also identified MHC-E alleles in five other New World monkey species, representing all extant platyrrhine families. In contrast to all other classical and nonclassical MHC class I genes in primates, the rate of synonymous nucleotide substitution is much greater than the rate of nonsynonymous nucleotide substitution within exons 2 and 3 encoding the peptide binding region (PBR) in MHC-E genes. DISCUSSION The PBR of the MHC-E molecule has evolved under purifying selective pressures, and the very unusual evolutionary history of this ancient gene provides further evidence that the products of the HLA-E locus serve a critical immunological function. FUTURE DIRECTIONS Given the remarkable conservation of the PBR during primate evolution, this critical immunological function is probably related to the peptide binding ability of the MHC-E protein. KEY WORDS MHC, HLA-E, New World FUNDING NIH RR00167, DK44886 PUBLICATIONS Knapp, LA, Cadavid, LF, and D.I. Watkins. 1998. The MHC-E locus is the most ancient and well-conserved of all known primate class I histocompatibility genes. J. Immunol. 160:189-196.