Fig 3. Constraints on the RNA organization consistent with the tomogram.

Each possible RNA organization is characterized by which long edges (Fig. 1B, purple edges) are occupied in the polyhedral shell of the icosahedrally-averaged density. Long connections are labelled by the numbers of the five-fold vertices (Fig. 1D) they connect (x•y connecting five-fold vertices x and y). Constraints imposed in the analysis are indicated in the first row, with green indicating an occupied edge, and red an unoccupied edge. The five paths meeting these constraints are characterized according to occupied and non-occupied edges. The last row shows edges shared by all five paths.