Characterization of composite motifs.

A: Histogram of the number of elementary motifs comprising composite motifs. B: Histograms of the average and minimum sequence identities (%) between pairs of subunits within each composite motif. C: Composite motif similarity as a function of minimum sequence identity between pairs of composite motifs. Sequence identity between two composite motifs is defined as the sequence identity between two protein sequences, one belonging to the one motif, the other to the other motif.