Figure 1.

(a) (left) 2D diagram of a three-way junction and (right) its 3D representation element composed of three helices labeled and color-coded by H₁ (red), H₂ (purple), and H₃ (green), and the corresponding single stranded loop regions labeled L1 to L3 with nucleotides color-coded in gray. Helices and loop regions are labeled in a unique way according to the 5′ to 3′ orientation of the entire RNA structure, by labeling H₁ as the first helix encountered, while entering the junction region, as one moves along the nucleotide chain in the 5′ to 3′ direction and so forth. (b) Histogram from a total of 216 RNA junctions sorted by branching degree ranging from 3 (3WJ) to 10 (10WJ).