Plays a role in RNA-mediated gene silencing by both micro-RNAs (miRNAs) and short interfering RNAs (siRNAs) (PubMed:22187428). Required for miRNA-dependent repression of translation and for siRNA-dependent endonucleolytic cleavage of complementary mRNAs by argonaute family proteins (PubMed:22187428). As a scaffolding protein, associates with argonaute proteins bound to partially complementary mRNAs, and can simultaneously recruit CCR4-NOT and PAN deadenylase complexes (By similarity). Interacts with AGO2. Interacts with AGO1, AGO3 and AGO4. Interacts with CNOT1; the interaction is direct and mediates the association with the CCR4-NOT complex. Interacts with ZC3H12A. Interacts with SND1. Interacts with GARRE1 (By similarity). Mammalian P-bodies are also known as GW bodies (GWBs). Detected in the yolk sac endoderm at embryonic stage 9.5 dpc. Development up until embryonic stage 9.5 dpc is normal. After this point, mortality rates increase rapidly with less than 5% survival at stage 12.5 dpc. The yolk sac endoderm is abnormally thin with fewer mitotic cells. In addition there are fewer blood islands in the yolk sac, associated with impaired hematopoiesis. Expression of many miRNA-regulated genes in the yolk sac is abnormal, and in particular there is marked derepression of genes involved in regulation of apoptosis and the cell cycle. miRNA biogenesis is not affected. Belongs to the GW182 family.