FIGURE 2.

The 5′ nucleotide of the guide strand and the length of the small RNA duplex determine sorting between Ago1 and Ago2. miRNA or siRNA duplexes that differ from each other only in their 5′ nucleotide (A) and length (B), but not their duplex structure, were assessed by UV crosslinking for their assembly into Ago1 or Ago2 RISC in vitro. Mean ± SD of three replicates is reported. (C) The 5′ nucleotide distribution for the hp-esiRNAs bound to Ago1 and Ago2 was deduced by analyzing the small RNA immunoprecipitated with Ago1 and Ago2 from S2 cell lysates or the small RNAs from fly heads immunoprecipitated with Ago1 and inferred to be bound to Ago2 by their resistance to oxidation.