The role of Sry in mammalian sex determination

The testis-determining gene is the Y-linked gene responsible for initiating the developmental pathway leading to testis formation in males. A strategy based on determining the precise chromosomal location of this locus has been used to clone a new gene which has been called SRY in humans (Sry in mice). A variety of studies now show that this is indeed the testis-determining gene. Sry has a spatial and temporal pattern of expression which correlates with the initiation of testis differentiation. The amino acid sequence encoded by the gene suggests that the protein may function as a transcription factor, which fits well with models of sex determination. Some cases of XY sex reversal in humans and mouse have been attributed to mutations in SRY/Sry, indicating that it is normally necessary for testis determination. The finding that a genomic fragment carrying Sry can cause male development in XX mice has proved that Sry is the only gene from the Y chromosome necessary for testis determination.