AGO2 and its partners: a silencing complex, a chromatin modulator, and new features.

AGO2 is the only member with catalytic activity in Argonaute family and contains four functional core domains, which are N domain, PAZ domain, MID domain, and PIWI domain from N-terminal to C-terminal. In traditional view, AGO2 serves as the catalytic engine of the RNA induced silencing complex and plays an important role in small RNAs guided post transcriptional gene silencing, including mRNA degradation and translational repression. Moreover, AGO2 also plays multiple roles in gene regulation processes in nuclei, such as chromatin remodeling, transcriptional repression and activation, double-strand break repair and alternative splicing. Recent studies have also implicated AGO2 in several other cellular processes, including alternative polyadenylation, translational activation, and transposon repression.