Required for female sex determination in somatic cells and for spermatogenesis in male germ cells. Positive regulator of female-specific splicing and/or polyadenylation of doublesex (dsx) pre-mRNA. Splicing requires an enhancer complex, dsxRE (dsx repeat element: which contains six copies of a 13-nucleotide repeat and a purine-rich enhancer (PRE)). DsxRE is formed through cooperative interactions between tra, tra2 and the sr proteins, and these interactions require both the repeat sequences and PRE. PRE is required for specific binding of tra2 to the dsxRE. Protein-RNA and protein-protein interactions are involved in tra-2 dependent activation and repression of alternative splicing. Together with tra-2, plays a role in switching fru splicing from the male-specific pattern to the female-specific pattern through activation of the female-specific fru 5'-splice site. Isoform Tmaj and isoform Tmin are expressed in males and females. Isoform msTmaj and isoform msTmin are present only in male germ cells. The RS2 (Arg/Ser-rich domain 2) and RNP-CS (ribonucleoprotein consensus sequence) domains are required for both male sterility and female-specific dsx splicing but the RS1 domain is dispensable. Extensively phosphorylated on serine residues in the RS domain. Belongs to the splicing factor SR family.