Heilig R, Perrin F, Gannon F, Mandel J L, Chambon P
Cell. 1980 Jul;20(3):625-37. doi: 10.1016/0092-8674(80)90309-8.
The X, Y and ovalbumin genes, which are found within a 40 kb region of the chicken genome, are all expressed in oviduct under steroid hormone control, and share some sequence homologies. We have now cloned the complete X gene and have analyzed its structure. It codes for two RNA species, X and X'; both are coded by eight exons and appear to differ only by the size of their 3' untranslated region, X' RNA being 1400 nucleotides longer than X RNA. The striking similarity in the number and length of the exons which constitute the X, Y or ovalbumin genes establishes that they have evolved from a common ancestor gene by duplication events. Comparison of selected regions of the X and ovalbumin genes indicates that the exon sequences coding for protein and the location of the splice junctions have been well-conserved. The introns and the 3' untranslated exonic sequences have diverged much more rapidly. Four regions of apparently unrelated repetitive sequences are found both outside the X gene and within it (in two introns and in the sequence coding for the 3' untranslated part of X'RNA). The intragenic repetitive sequences have no counterpart in the ovalbumin and Y genes.
X、Y和卵清蛋白基因位于鸡基因组的一个40 kb区域内，它们在类固醇激素的控制下均在输卵管中表达，并且具有一些序列同源性。我们现已克隆出完整的X基因并分析了其结构。它编码两种RNA，即X和X'；二者均由八个外显子编码，似乎仅在3'非翻译区的大小上有所不同，X' RNA比X RNA长1400个核苷酸。构成X、Y或卵清蛋白基因的外显子数量和长度惊人地相似，这表明它们是通过复制事件从一个共同的祖先基因进化而来的。对X基因和卵清蛋白基因特定区域的比较表明，编码蛋白质的外显子序列和剪接位点的位置一直保持得很好。内含子和3'非翻译外显子序列的分歧要快得多。在X基因之外及其内部（两个内含子以及编码X'RNA 3'非翻译部分的序列中）均发现了四个明显不相关的重复序列区域。基因内的重复序列在卵清蛋白和Y基因中没有对应物。
