(Left panel) The proposed features of the postulated model of the cleavage-competent complex are as follows: The Dicer-specific helix is disrupted, with the RNA duplex directed towards the protein. The 2-nt 3′-overhang is positioned in the 3′-pocket, with disruption of the terminal mismatch pair most likely facilitates positioning of the 5′-phosphate in the phosphate pocket. (Right panel) The unique features of the structure tentatively assigned to the product release/transfer complex are as follows: The Dicer-specific helix adopts a knob-like structure, thereby directing the RNA duplex away from the protein. The 2-nt 3′-overhang remains positioned in the 3′-pocket, while the 5′-phosphate is released from the phosphate pocket, which is now occupied by a sulfate/phosphate from the buffer.