Basepairs involving Hoogsteen(H) edge of Adenine and Hoogsteen(H) edge of Uracil is shown. Highlighted examples are found from RNA crystal structures obtained from PDB.
Base pairs stabilized by C-H...N/O interactions along with N-H...N/O hydrogen bonds
| Basepair  (type & Orientation) | *Frequency | Example | Hydrogen bonding atoms with their
   precursors | 
| 0 | Optimized Model Structure | N1-N6...O4-N3 C4-N7...C5-N1 | |
| 8 | Optimized Model Structure | C4-N7...C5-N1 C4-C8...O4-N3 |