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. Author manuscript; available in PMC: 2007 Mar 15.
Published in final edited form as: Annu Rev Biochem. 2001 Nov 9;71:817–846. doi: 10.1146/annurev.biochem.71.110601.135501

Figure 4.

Figure 4

ADARs are capable of a wide range of specificities depending on the structure of the RNA substrate. (a) RNAs that are predicted to form rod-shaped molecules of similar lengths. While an 800– base-pair dsRNA is deaminated promiscuously by an ADAR, the ~1700 nucleotide HDV antigenome is specifically targeted at the amber/W site (red). (b) ADARs (green) reacting with four dsRNAs of differing stabilities. Because ADARs change AU base-pairs to IU mismatches, ADAR substrates become increasingly single-stranded as the reaction proceeds. The model proposes that an ADAR reaction stops when the RNA is too single-stranded to be bound by an ADAR. Substrates that are shorter, or contain mismatches, are more selectively deaminated because it takes fewer deaminations to reach the critical “thermodynamic” threshold. In the far left and far right panels blue lines represent a specific sequence. The sequence is modified more selectively when placed between internal loops, as in the barbell molecule.