Plays a functionally redundant role in shifting germ cell sexual differentiation in hermaphrodites. Extensively phosphorylated on serine residues in the RS domain. RNA-mediated interference (RNAi) of rsp-5/rsp-6 resulted in fertile animals that exhibit excessive sperm and delayed oocyte production, and sterile animals that develop morphological abnormalities of somatic gonads. Belongs to the splicing factor SR family.