Table 2.

Fraction of nucleotides in the 5S, 16S and 23S rRNA 3D structures of E. coli (PDB files: 2aw4 and 2avy) and T. thermophilus (PDB files: 2j01 and 1j5e) and the 5S and 23S rRNAs of H. marismortui (PDB file: 1s72) that form cWW and non-cWW base pairs, base-stacking and base–phosphate interactions

Bases forming base pairs
cWW base pairs and no non-cWW base pair	52%
cWW base pairs and at least one non-cWW base pairs	7%
At least one non-cWW base pairs and no cWW base pairs	20%
Bases forming other interactions (no base pairing)
Base-stacking and base–phosphate interaction	13%
Base–stacking only	3%
Base–phosphate only	1%
Bases forming no RNA–RNA interactions	4%
Total	100%