Required for gene silencing mediated by micro-RNAs (miRNAs). Silences both polyadenylated and deadenylated mRNAs. Required for miRNA-mediated translational repression and mRNA decay. Not required for miRNA target recognition. Necessary to initiate but not to maintain silencing. Promotes mRNA deadenylation through the recruitment of the CCR4-NOT and PAN complexes and promotes decapping by the DCP1-DCP2 complex. Dissociates from silenced mRNAs after deadenylation. Required for completion of nuclear divisions during early embryonic development. Interacts (via N-terminal region) with AGO1 (via Piwi domain); the interaction is essential for localization of AGO1 in P-bodies and for miRNA-mediated silencing. Interacts with pAbp/PABPC1; this interaction interferes with the binding of pAbp to eIF4G and is required for miRNA-mediated silencing. Interacts with CCR4-NOT complex members Not1, Rga/NOT2, twin/CCR4, Pop2 and NOT3/5 and with PAN complex members CG8232/PAN2 and CG11486/PAN3. Highest levels are found during early embryonic development until approximately 18 hours and during pupariation. The UBA domain is not required for correct subcellular location, gene silencing or interaction with pAbp. The RRM domain lacks RNA-binding properties and does not bind RNA in vitro. It is not required for P-body localization or for interaction with AGO1 or miRNAs but is required for silencing. May play a role in protein-protein interactions. Belongs to the GW182 family. Truncated N-terminus.