Plays a role in RNA-mediated gene silencing by both micro-RNAs (miRNAs) and short interfering RNAs (siRNAs). Required for miRNA-dependent translational repression and siRNA-dependent endonucleolytic cleavage of complementary mRNAs by argonaute family proteins. As scaffolding protein associates with argonaute proteins bound to partially complementary mRNAs and simultaneously can recruit CCR4-NOT and PAN deadenylase complexes. Interacts with AGO1, AGO2, AGO3 and AGO4. Interacts with CNOT1; the interaction mediates the association with the CCR4-NOT complex. Interacts with PAN3; the interaction mediates the association with the PAN complex. Interacts with MOV10; the interaction is direct and RNA-dependent. Mammalian P-bodies are also known as GW bodies (GWBs). Belongs to the GW182 family.