Recombinant Ago2: pre-miR-138-2 and Ago2:73nt ssRNA complexes direct 5' - and 3' -arm target cleavage. A. Results of cleavage assay with recombinant Ago2 pre-incubated with gel-extracted 5' -P-pre-miR-138-2, before the addition of radiolabeled gel-purified RNA targets complementary to its 5' - (Tb-5) or 3' -arm (Tb-3). Predicted size of 5' - cleavage product of Tb-5 and Tb-3 is 17 nt and 16 nt respectively. B. Experiments were performed as in (A), except that a gel-purified 73nt single-stranded (ss) RNA was pre-incubated with Ago2 before the addition of radiolabeled 5' -end (Tc-5) or 3' -end target (Tc-3). Predicted sizes of 5' - end cleavage products of 5' -arm and 3' -arm targets are 60 nt and 15 nt respectively.