DEAD-box proteins, characterized by the conserved motif Asp-Glu-Ala-Asp, are putative RNA helicases implicated in several cellular processes involving modifications of RNA secondary structure and ribosome/spliceosome assembly. Based on their distribution patterns, some members of this family may be involved in embryogenesis, spermatogenesis, and cellular growth and division. DDX59 (DEAD box protein 59), also known as ZNHIT5 (zinc finger HIT domaincontaining protein 5), is a 619 amino acid member of the DEAD box helicase protein family. Like many DEAD box helicase family members, DDX59 contains a Q motif, which controls ATP binding and hydrolysis. Expressed as two isoforms produced by alternative splicing, DDX59 contains one helicase C-terminal domain and one HIT-type zinc finger.