Tucker P K, Lundrigan B L
Museum of Zoology, Ann Arbor, Michigan.
Nature. 1993 Aug 19;364(6439):715-7. doi: 10.1038/364715a0.
The Y chromosome-linked sex determining locus (Sry) responsible for testis determination in mammals contains a DNA-binding motif (HMG box) that is conserved across species of marsupial and placental mammals (infraclasses Metatheria and Eutheria, respectively). But little to no sequence similarity is observed in flanking sequences between these two infraclasses, or among orders within each infraclass. We investigated the rate and pattern of evolution for the coding sequence of Sry in Old World mice and rats (subfamily Murinae). We found typical rates of synonymous substitution throughout the gene, but high rates of non-synonymous substitution, especially in the C-terminal (non-HMG box) region, when compared to other genes. This region is also characterized by a frame-shift mutation and variation in a trinucleotide repeat motif. These data suggest that the non-box region is either functionally unconstrained or has undergone species-specific adaptive divergence.
在哺乳动物中，负责睾丸决定的Y染色体连锁性别决定基因座（Sry）包含一个DNA结合基序（HMG盒），该基序在有袋类和胎盘类哺乳动物（分别为后兽亚纲和真兽亚纲）的物种间保守。但在这两个亚纲的侧翼序列之间，或每个亚纲内的目之间，几乎没有观察到序列相似性。我们研究了旧大陆小鼠和大鼠（鼠亚科）中Sry编码序列的进化速率和模式。我们发现整个基因的同义替换率是典型的，但与其他基因相比，非同义替换率很高，尤其是在C端（非HMG盒）区域。该区域还具有一个移码突变和一个三核苷酸重复基序的变异。这些数据表明，非盒区域要么在功能上没有受到限制，要么经历了物种特异性的适应性分化。
