Figure 1.

Illustration on calculation of mutual information. Illustration on calculation of mutual information between positions i and j in multiple sequence alignments for protein amino acid sequence A and RNA base sequence B. In this figure, an arrow indicates that sequences connected with each other by the arrow belong to the same organism, and the third sequence in the alignment for RNA B is ignored in calculation of mutual information because it does not have a partner protein sequence of the same organism. Sequences A and B are shown at the first line of multiple sequence alignments, respectively, and gaps inserted by alignment algorithms are deleted with the columns.