Sex differentiation protein controlling female somatic sexual differentiation (PubMed:19841093, PubMed:28495751). May act by promoting the formation of a splicing enhancer complex (By similarity). The sexual regulation of tra occurs through a mechanism of sex-specific alternative mRNA splicing. The active state of tra is initially established by maternally provided tra (PubMed:19841093). Once activated, zygotic tra perpetuates its female-promoting function by a positive splicing feedback loop throughout development (PubMed:19841093). The splice forms expressed in males is not translated: splice form expressed in males is regulated by the male determiner protein Mdmd (PubMed:28495751).