Distances of nearest phosphosites. (A) Analysis of ~51,000 non- redundant S/T phosphosites from unique proteins (B) Analysis of ~3160 non-redundant Y phosphosites. For each distance, the frequency is shown relative to the frequency of randomly selected from the relevant amino acids (see Methods). (C) Analysis of S/T phosphosites as in A, the distance to the nearest Y phosphosite is reported. The tail distribution of phosphosites including a distance >30 amino acids is provided in Additional file 5.