An SRY-related sequence on the marsupial X chromosome: implications for the evolution of the mammalian testis-determining gene.
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of X chromosome-Y chromosome differentiation initiated at the locus of an original sex-determining gene(s), later superseded by SRY.
Foster
J W
JW
Department of Genetics and Human Variation, LaTrobe University, Bundoora, Victoria, Australia.
Graves
J A
JA
D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D004247:DNA / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D004303:Dosage Compensation, Genetic; D005260:Female; D006609:High Mobility Group Proteins / Q000235:genetics; D006801:Humans; D008297:Male; D008394:Marsupialia / Q000196:embryology / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D015183:Restriction Mapping; D055748:SOXB1 Transcription Factors; D012733:Sex Differentiation / Q000235:genetics*; D051876:Sex-Determining Region Y Protein; D013737:Testis / Q000196:embryology*; D014157:Transcription Factors; D014960:X Chromosome; D014998:Y Chromosome
D004268:DNA-Binding Proteins; D006609:High Mobility Group Proteins; D009687:Nuclear Proteins; C527785:SOX3 protein, human; D055748:SOXB1 Transcription Factors; C497745:SRY protein, human; D051876:Sex-Determining Region Y Protein; C527786:Sox3 protein, mouse; C497746:Sry protein, mouse; D014157:Transcription Factors; D004247:DNA