Figure 2. The top ten highest MI triplets for U519 (2A, red) and C487 (2B, yellow) form a connected series across the protein structure (standard E.coli numbering).

Both U519 and C487 form base pairs with other 23S nucleotides, and thus all interactions are via backbone atoms. Many of the amino acids in the high MI clusters are at the edges of secondary structure elements. Other nucleotides did not have high MI triplets clustered in 3D space.