Essential for the formation of P-bodies, cytosolic membrane-less ribonucleoprotein granules involved in RNA metabolism through the coordinated storage of mRNAs encoding regulatory functions. Plays a role in P-bodies to coordinate the storage of translationally inactive mRNAs in the cytoplasm and prevent their degradation. In the process of mRNA degradation, plays a role in mRNA decapping. Blocks autophagy in nutrient-rich conditions by repressing the expression of ATG-related genes through degradation of their transcripts. ATP + H2O = ADP + H(+) + phosphate Interacts with LSM14A, LSM14B, EIF4ENIF1/4E-T, PATL1, EDC3 and EDC4 (By similarity). Forms a complex with DCP1A, DCP2, EDC3 and EDC4/HEDLS. Interacts with LIMD1, WTIP and AJUBA. Interacts with APOBEC3G in an RNA-dependent manner (By similarity). Interacts with RC3H1 (By similarity). Interacts with ATXN2L. Interacts with MCRIP1. Interacts with MCRIP2. Interacts with NUFIP2. Interacts with TRIM71 (via NHL repeats) in an RNA-dependent manner (By similarity). Imported in the nucleus via interaction with EIF4ENIF1/4E-T via a piggy-back mechanism. Upon cellular stress, relocalizes to stress granules. Sumoylated. Belongs to the DEAD box helicase family. DDX6/DHH1 subfamily.