Figure 3. (A) Segmented map of human Dicer with crystal structures of homologous domains docked. (B) Model for pre-miRNA recognition. A pre-miRNA hairpin is modeled into the proposed binding channel of Dicer, with the stem-loop fit in the RNA-binding cleft of the protein. (C) Schematic for processive dicing in which dsRNA is translocated into the nuclease core (1). The PAZ domain (purple) recognizes the dsRNA end, positioning RNase III (orange) for cleavage (2). The siRNA product is released while the dsRNA substrate remains bound to the protein (3). Reprinted with permission from Lau et al.⁴⁴