DDX5 is a member of the DEAD box family of proteins that possesses several conserved motifs which include the highly conserved DEAD (Asp-Glu-Ala-Asp) amino acid sequence motif. The major activity of DEAD box proteins is to function as ATP-dependent RNA helicases. As helicases, DEAD proteins play an important role in all aspects of RNA metabolism and function which include pre-mRNA splicing, RNA synthesis, RNA degradation, RNA export, RNA translation, RNA secondary structure formation, ribosome biogenesis, and the assembly of RNP complexes. Some members of the DEAD box proteins also exhibit functions involved in transcriptional regulation. In addition to a role involved in RNA splicing, DDX5 has been observed to interact with and act as a transcriptional coactivator for estrogen receptor alpha (ERalpha). DDX5 has also been found to interact with CBP/300, Smad3, and p53 to modulate transcription. DDX5 is closely related to and forms heterodimers with DDX17.