Structural insight into the mechanism of double-stranded RNA processing by ribonuclease III (Gan J, Tropea JE, Austin BP, Court DL, Waugh DS, and Ji X. Cell 2006; 124:355-366. Abstract). The highly symmetric structure of an RNase III-product complex reveals that the dimerization of the two endoNDs is essential for the formation of two RNA cleavage sites precisely arranged to produce the characteristic 2-nucleotide 3′ overhang of RNase III products. The two endoNDs are shown as molecular surface; the two dsRBDs are illustrated as ribbon diagrams (helices as spirals, b-strands as arrows, and loops as pipes) and colored in cyan and orange, respectively. The Mg²⁺ ions are indicated with green spheres; the two cleaved RNA strands are shown as tubes in blue and red, respectively.