Table 1.

The statistics of phosphorylation sites obtained from Phospho.ELM and Swiss-Prot

Data source	Number of phosphorylated proteins	Number of phosphorylation sites
		Serine (S)	Threonine (T)	Tyrosine (Y)	Histidine (H)	Total
Phospho.ELM	3674	9917	1890	1804	1	13 612
Swiss-Prot*	3148	4846	1035	901	42	6832
Combined (non-redundant)	5842	11 888	2433	2179	43	16 551

It notices that the sum of serine, threonine, tyrosine and histidine in Swiss-Prot is not equal to 6832, because there are several phosphorylation sites located on other kinds of residue. *The entries which contain residues annotated as ‘phosphorylation’ in the ‘MOD_RES’ are extracted and the entries annotated as ‘by similarity’, ‘potential’ and ‘probable’ are excluded.