In females, the Sxl gene product (SXL) binds to premRNA of the transformer (tra) gene, and directs its splicing to produce a female-specific TRA protein, which combines with the TRA-2 protein to direct female-specific splicing of dsx pre-mRNA, resulting in a female-specific protein (DSX-F).

In males, the absence of SXL results is a male-specific processing of tra pre-mRNA, producing no functional TRA protein, which in turn leads to male-specific processing of dsx transcripts and a male-specific (DSX-M) protein that activates the pathway for male sexual development.