Figure 6. Average polar residue content versus charged residue content in FG Nups and Disprot proteins.

For FG Nups, only FG linkers with the length of 10 to 30 residues are taken into account. For Disprot proteins, random sequences of 10–30 residues long are selected from Disprot proteins. For the sake of simplicity, these sequences from both groups are called linkers. Each point indicates the average number of polar residues among all linkers falling within that specific range of charged residue densities. Data points with at least 50 samples are shown (FG linkers with charged residue number densities of higher than 0.7 are excluded). Pie charts show average charged residue number density (red), average polar number density (dark brown), and average hydrophobic residue number density (cream) for the corresponding data point. Average number density of polar residues in FG Nups displays a sharp decreasing trend with respect to an increase in the number density of charged residues as compared to Disprot proteins, implying that FG Nups are more likely to have polar residues as the number of charged residues decreases. Disprot proteins are compared to FG Nups as a control group to show the significance of the observed evolutionarily conserved trend.