P68-Protein

P68 (DDX5) is considered a prototypical member of the DEAD-box family of RNA helicases. It was discovered by chance through cross-reaction with an antibody against simian virus SV-40 T antigen and shares extensive amino acid sequence homology with the eukaryotic translation initiation factor eIF-4A, the first helicase identified that can unwind RNA. Soon, it was reported that p68 is an RNA-dependent ATPase and also has RNA unwinding activity.

The DEAD-box family of RNA helicases contains nine domains with strong peptide sequence conservation, including the Asp-Glu-Ala-Asp (DEAD) helicase signature sequence. In addition to regulating the conformation of RNA structure and the known ATP-dependent RNA helicase activity, DEAD box-containing proteins are required for a variety of processes in which RNA is involved, including ribosome biogenesis, embryogenesis, spermatogenesis, and cell development and division.

There is ample evidence that p68 is an important co-activator of transcription factors, e.g. estrogen receptor α (ERα), MyoD, Runx2, androgen receptor (AR), and p53 , which have clear roles in cancer. Recent studies have also shown that p68 is abnormally expressed/altered in various cancers, suggesting that p68 plays an important role in cancer development and progression.

1. Fuller-Pace FV et al. (2011) RNA helicases p68 and p72: multifunctional proteins with important implications for cancer development. Future Oncol 7: 239-251.