Summary of the number and coverage of parameterized PTMs.

<p>a) the number of parameterized PTMs by type (outer annulus) together with the number of parameterized non-redundant compounds by type (inner circle), labeled accordingly (number of PTMs: number of compounds); b) the number of experimentally verified PTMs by type annotated in the UniProt database (total of 72,984); c) coverage of experimentally verified PTMs shown as percentages with the values and the number of covered modifications displayed (top of bars). Color code: phosphorylation-red, acetylation-blue, methylation-yellow, hydroxylation-green, other PTMs-orange, terminal PTMs-gray and all-white.