Chandra H S
Mol Gen Genet. 1984;193(3):384-8. doi: 10.1007/BF00382072.
A model is suggested for mammalian male determination based on interactions postulated to occur among an autosomal repressor gene, an X-linked male-determining gene termed Tdx, and multiple copies of certain DNA sequences on the Y chromosome that do not code for any protein. The repressor, synthesised in limited amounts, has higher affinity for the Y-linked sequences than for Tdx and its affinity for Tdx is greater than that of RNA polymerase. In XY cells the Y effectively binds all available repressor, permitting transcription of Tdx to occur. In XX cells, since competition from the Y-linked high-affinity sequences is absent, the repressor binds to Tdx and prevents transcription. As a result of this competition between Tdx and the Y-linked high-affinity sites for limiting concentrations of the autosomal repressor, the product of the Tdx gene (TDX) is synthesized in the male but not in the female. It is suggested that in determination of the male sex, the role of the Y chromosome is to serve as a sink for the Tdx repressor. The proposed interactions provide a plausible explanation for the genetic properties of several anomalies of sexual development in mouse, man, and other mammals. The model suggests that the postulated multiple, high-affinity sequences on the Y chromosome of the mouse are included among the DNA sequences referred to as the Sxr-Bkm sequences.
基于常染色体抑制基因、一个名为Tdx的X连锁雄性决定基因以及Y染色体上某些不编码任何蛋白质的特定DNA序列的多个拷贝之间假定发生的相互作用，提出了一种哺乳动物雄性决定模型。抑制因子合成量有限，它对Y连锁序列的亲和力高于对Tdx的亲和力，且它对Tdx的亲和力大于RNA聚合酶对Tdx的亲和力。在XY细胞中，Y有效地结合了所有可用的抑制因子，使得Tdx能够转录。在XX细胞中，由于不存在来自Y连锁高亲和力序列的竞争，抑制因子与Tdx结合并阻止转录。由于Tdx与Y连锁高亲和力位点竞争常染色体抑制因子的有限浓度，Tdx基因的产物（TDX）在雄性中合成而不在雌性中合成。有人提出，在雄性性别的决定中，Y染色体的作用是作为Tdx抑制因子的汇聚点。所提出的相互作用为小鼠、人类和其他哺乳动物中几种性发育异常的遗传特性提供了一个合理的解释。该模型表明，小鼠Y染色体上假定的多个高亲和力序列包含在被称为Sxr - Bkm序列的DNA序列中。
