Plays a role in RNA-mediated gene silencing by both micro-RNAs (miRNAs) and short interfering RNAs (siRNAs). Required for miRNA-dependent repression of translation and for siRNA- dependent endonucleolytic cleavage of complementary mRNAs by argonaute family proteins. As scaffoldng protein associates with argonaute proteins bound to partially complementary mRNAs and simultaneously can recruit CCR4-NOT and PAN deadenylase complexes. {ECO:0000269|PubMed:16284622; ECO:0000269|PubMed:16284623; ECO:0000269|PubMed:17596515; ECO:0000269|PubMed:17671087; ECO:0000269|PubMed:19056672; ECO:0000269|PubMed:19304925}.