Figure 1. Amino acid determinants defining structural and functional differences between the ordered and intrinsically disordered proteins. (A) Amino acid compositions of several data sets discussed in the text (DisProt,⁴⁴ UniProt,⁴⁵ PDB Select 25⁴⁶ and surface residues³⁷). (B) Fractional difference in the amino acid composition (compositional profile) between the typical IDPs from the DisProt database⁴⁴ and a set of completely ordered proteins⁴⁶ calculated for each amino acid residue. The fractional difference was evaluated as (C_DisProt-C_PDB)/C_PDB, where C_DisProt is the content of a given amino acid in a DisProt databse, and C_PDB is the corresponding content in the data set of fully ordered proteins. Positive bars correspond to residues found more abundantly in IDPs, whereas negative bars show residues, in which IDPs are depleted. Amino acid types were ranked according to their decreasing disorder-promoting potential.³⁶