MHC class II genes of a marsupial, the red-necked wallaby (Macropus rufogriseus): identification of new gene families.
MHC class II genes of a marsupial, the red-necked wallaby (Macropus rufogriseus): identification of new gene families.
复制标题
有袋动物红颈袋鼠 (Macropus rufogriseus) 的 MHC II 类基因：新基因家族的鉴定。
DOI：
10.1093/oxfordjournals.molbev.a040688
复制
发表时间：
1991
影响因子：
10.7
通讯作者：
Klein,J
中科院分区：
文献类型：
--
作者：
Schneider,S;Vincek,V;Tichy,H;Figueroa,F;Klein,J
在胎盘哺乳动物中，主要组织相容性复合体（Mhc）的II类区域由几个基因家族组成，这些基因家族在不同的物种中表现出同源关系。由于这些家族与鸟类的Mhc II类β链编码基因家族不是同源的，因此不同的哺乳动物家族一定是在鸟类和哺乳动物分离之后大约250 Mya但在胎盘哺乳动物辐射之前（60-80 Mya）分化的。为了进一步了解哺乳动物中II类基因的起源，我们研究了作为有袋动物代表的小袋鼠的β链编码基因，该基因从胎盘哺乳动物中分离出来，大约125 Mya。以黑猩猩DRB基因为探针，从红颈袋鼠（Macropus rufogriseus）cDNA文库中克隆了3个β链编码基因，并测定了它们的核苷酸序列。这些基因与迄今为止研究的哺乳动物中的任何基因都不是直系同源的，而是属于我们命名为Maru-DAB和Maru-DBB的两个新家族。三个序列之一（DAB 2）似乎来自转录的假基因;它缺乏指定β 2结构域的前51个氨基酸残基的密码子。DAB和DBB家族迄今为止尚未在胎盘哺乳动物中发现，并且DOB、DPB、DQB或DRB基因似乎在一个代表性有袋动物物种中均不表达，这一事实可以解释为表明真兽目和后生兽目哺乳动物的II类基因家族是从不同的祖先基因进化而来的。
In placental mammals, the class II region of the major histocompatibility complex (Mhc) consists of several gene families which show orthologous relationships in the different species. As these families are not orthologous with the Mhc class II beta-chain-encoding gene families of birds, the different mammalian families must have diverged after the separation of birds and mammals approximately 250 Mya but before the radiation of placental mammals (60-80 Mya). To obtain further information about the origin of the class II genes in mammals, we studied the beta-chain-encoding genes of the wallaby as a representative of marsupials, which split from placental mammals approximately 125 Mya. Three beta-chain-encoding genes were isolated from a red-necked wallaby (Macropus rufogriseus) cDNA library by using a chimpanzee DRB probe, and their nucleotide sequences were determined. The genes are not orthologous to any of the genes in mammals studied thus far but belong to two new families which we designated Maru-DAB and Maru-DBB. One of the three sequences (DAB2) seems to be derived from a transcribed pseudogene; it lacks the codons specifying the first 51 amino acid residues of the beta 2 domain. The fact that the DAB and DBB families have thus far not been found in placental mammals and that none of the DOB, DPB, DQB, or DRB genes seems to be expressed in the one representative marsupial species can be interpreted as suggesting that class II gene families of eutherian and metatherian mammals evolved from different ancestral genes.