Figure 2

Relative amino acid abundance of lysine (K) at 5' ends of exons in six species. Proportional usage of lysine vis-à-vis all other amino acids is plotted against distance from the exon-intron boundary measured in amino acids. Variable degrees of preference for lysine near the boundary are evident for non-nematode species (Am, rho = -0.67, P = 2.71E-05, β(slope) = -0.017; Dr, rho = -0.79, P = 6.51E-07, β = -0.035; Dm, rho = -0.65, P = 6.11E-05, β = -0.020; Hs, rho = -0.90, P = 3.67E-09, β = -0.041) whereas nematodes show strong avoidance trends (Ce, rho = 0.89, P = 5.26E-08, β = 0.030; Cb, rho = 0.92, P = 0, β = 0.033).