May play a role in germ cell development. May play a role in sperm motility. Found in a mRNP complex, at least composed of TDRD1, TDRD6, TDRD7 and DDX4. N-terminus interacts with RANBP9. Interacts with PIWIL2 and MAEL. Expressed only in ovary and testis. Expressed in migratory primordial germ cells in the region of the gonadal ridge in both sexes. Belongs to the DEAD box helicase family. DDX4/VASA subfamily. 2 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.