Foster J W, Graves J A
Department of Genetics and Human Variation, LaTrobe University, Bundoora, Victoria, Australia.
Proc Natl Acad Sci U S A. 1994 Mar 1;91(5):1927-31. doi: 10.1073/pnas.91.5.1927.
The SRY gene on the human, mouse, and marsupial Y chromosomes is the testis-determining gene that initiates male development in mammals. The SRY protein has a DNA-binding domain (high mobility group or HMG box) similar to those found in the high-mobility-group proteins. SRY is specific for the Y chromosome, but many autosomal genes have been identified that possess a similar HMG box region; those with the most closely SRY-related box regions form a gene family now referred to as SOX genes. We have identified a sequence on the marsupial X chromosome that shares homology with SRY. Sequence comparisons show near-identity with the mouse and human SOX3 gene (formerly called a3), the SOX gene which is the most closely related to SRY. We suggest here that the highly conserved X chromosome-linked SOX3 represents the ancestral SOX gene from which the sex-determining gene SRY was derived. In this model SOX3/SRY divergence and the acquisition of a testis-determining role by SRY might have preceded (and initiated) sex chromosome differentiation or, alternatively, might have been a consequence of X chromosome-Y chromosome differentiation initiated at the locus of an original sex-determining gene(s), later superseded by SRY.
人类、小鼠和有袋类动物Y染色体上的SRY基因是启动哺乳动物雄性发育的睾丸决定基因。SRY蛋白具有一个DNA结合结构域（高迁移率族或HMG框），类似于在高迁移率族蛋白中发现的结构域。SRY对Y染色体具有特异性，但已鉴定出许多常染色体基因也拥有类似的HMG框区域；那些与SRY相关框区域最接近的基因形成了一个基因家族，现在称为SOX基因。我们在有袋类动物X染色体上鉴定出了一段与SRY具有同源性的序列。序列比较显示，它与小鼠和人类的SOX3基因（以前称为a3）几乎完全相同，SOX3基因是与SRY关系最密切的SOX基因。我们在此提出，高度保守的X染色体连锁SOX3代表了性决定基因SRY所源自的祖先SOX基因。在这个模型中，SOX3/SRY的分化以及SRY获得睾丸决定作用可能先于（并启动了）性染色体分化，或者，也可能是在原始性决定基因位点启动的X染色体 - Y染色体分化的结果，后来被SRY所取代。
