Table I Description of histone PTM frequency, co-frequencies and interplay values
ObservableDescriptionFormula
Peptide PTMsModified residues r and their PTMs mm→ = {(r1, m1), (r2, m2), …, (rn, mn)}
Peptide frequencyNumber of peptides with PTMs →mFm
Total peptide numberAll peptidesEmbedded Image
FrequencyNumber of peptides with PTM a on residue rFa,r = F(a,r) in m
Co-frequencyNumber of peptides with PTMs (a, r) and (b, s)Fa,r;b,s = F{(a,r), (b,s)} in m
Interplay valueNormalized frequency of PTMs (a, r) and (b, s)Embedded Image