a protein required for the 5' a?? 3' pathway of mRNA decapping and degradation-based post-transcriptional gene silencing. The proteins involved in 5' a?? 3' mRNA decay include DCP2, DCP1A, EDC3, EDC4 and DDX6, and are concentrated in cytoplasmic structures called mRNA "processing bodies" (P-bodies). Shortening of the 3'-poly(A) tail and removal of PABP precedes cleavage of the 5'-mRNA cap by a complex containing decapping enzymes 1A and 2 (DCP1A/DCP2). EDC4 enhances the catalytic activity of DCP2 in vitro. Shown to be required for silencing by miRNAs in Drosophila melanogaster. Two alternatively spliced human isoforms have been described. Note: This description may include information from UniProtKB.