A. The base sequences and numbering of base pairs in the RNA-DNA hybrids investigated in the present work. The DNA strands are in regular fonts and the RNA strands are in italic fonts. The base pairs from the two GC-rich dyadic sequences are shown in bold. In hybrid I, the base pairs are numbered in the 5’->3’ direction of the DNA strand. To emphasize the similarity in base sequence, in hybrid II, the base pairs are numbered in the opposite direction (5’->3’ in the RNA strand).
B. The structures of the G-C and A-T/A-U base pairs. The imino proton in each base pair is circled.