Involved in RNA-mediated gene silencing (RNAi) of mobile elements and repeats including retroposons SLACS (Spliced Leader Associated Conserved Sequence), TATE (Telomere-Associated Transposable Element) and TAS-like sequences (Telomere Associated Sequence), and a family of 74-nucleotide long tandem repeats, CIR74 (PubMed:21060810, PubMed:23217017). Predominantly binds to siRNAs derived from SLACS and TATE transposable elements and to a lesser extent to siRNAs from TAS-like and CIR74 elements (PubMed:23217017). RNAi-mediated knockdown reduces RNAi activity (PubMed:21060810, PubMed:23217017). Levels of mobile elements TATE, SLACS, TAS-like and repeat element CIR74 siRNAs are reduced (PubMed:23217017). Belongs to the argonaute family.