Figure 2.

(A) Comparison of abundance of the most order-promoting and the most disorder-promoting amino acids in FG Nups versus DisProt. FG Nups have a lower abundance of all of the order-promoting amino acids except for F. The sums of the abundance of order-promoting amino acids are nearly equal. On the other hand, the abundance of all of the charged residues is lower in FG Nups compared with DisProt. The abundance of the analyzed amino acids is very similar in DisProt and disorder prediction of UniProt. Therefore, they compare similarly with FG Nups (please see Fig. S2). (B) A snapshot of a small part of the schematic comparing charged residue distribution in FG Nups versus DisProt (the entire schematic was too large to be presented). The figure shows that FG Nups have a lower charged residue density compared to DisProt and that DisProt has a lower average length compared to FG Nups. The most interesting difference is that in the FG Nup sequences, several regions can be observed that are extensively large segments of the protein that have a low charge density and only have positively charged residues. Some of these regions are boxed with red. We have named these regions longest positive like charge regions (lpLCRs). The proteins in the FG Nups data set depict this pattern very frequently. Many of the FG Nups have two segments in their sequence; one is charge rich (similar to sequences in DisProt), and the other has a low density of charged residues that are almost always positively charged (lpLCR, the boxed pattern). Some of the FG Nups also do not contain the charge-rich part and are only composed of an lpLCR. To see this figure in color, go online.