Fig. 9.

Register variability between sequence specific contacts from helix α1 and loop 2. Structure superposition of ADAR2 dsRBD1 (blue) and dsRBD2 (red) and of the dsRBD of Aa RNase III (grey) (PDB codes 2L3C, 2L2K and 2EZ6). The glutamine side chain (Aa RNase III dsRBD), the methionine side chain (ADAR2 dsRBD1 and 2) from helix α1 and the peptide backbone carbonyl of loop 2, which make sequence-specific contacts with the RNA bases in the minor groove are represented as sticks. The variety of registers observed in these three structures mainly results from the different position of the glutamine (position 11) and the two methionines (position 4) on helix α1 (Fig. 7c, d)