Plays a major role in controlling sexual cell fates (PubMed:8889523, PubMed:11250902, PubMed:24098152). Promotes female development in XX animals where it sequesters one or more of the FEM proteins to the membrane thereby freeing the tra-1 protein (a putative transcription factor) to enter the nucleus and promote female development (By similarity). In XO animals it acts as a receptor for her-1 which prevents it from binding to FEM proteins thereby repressing the activity of tra-1 (By similarity). Negatively regulates male development when bound to fem-3 and is required together with tra-1 for promoting spermatogenesis (PubMed:12477393). Also required for feminizing tra-3 activity (By similarity). Interacts with tra-1 and fem-3. A number of isoforms are produced. Null hermaphrodite mutants have masculinized germ lines, producing only sperm. Animals make incomplete male tails, producing shorter stubby tails that lack sensory structures called rays.