. 2009 Jun 23;2:111. doi: 10.1186/1756-0500-2-111

Table 1.

The statistics of experimental PTM sites and putative PTM sites in this study.

PTM types	Modified residues	No. of experimental sites	No. of putative sites from UniProtKB/Swiss-Prot	No. of HMM-predicted sites in dbPTM
Phosphorylation	Serine, threonine, tyrosine, and histidine	31,363	36,080	1,815,472

N-linked Glycosylation	Asparagine and lysine	3,264	77,571	179,955

O-linked Glycosylation	Lysine, praline, serine, threonine, and tyrosine	1,896	2,558	386,545

C-linked Glycosylation	Tryptophan	53	52	4,015

Acetylation	N-terminal of some residues and side chain of lysine or cysteine	2,080	5,143	1,206

Amidation	Generally at the C-terminal of a mature active peptide after oxidative cleavage of last glycine	2,150	1,117	24,352

Hydroxylation	Generally of asparagine, aspartate, proline or lysine	1,033	1,074	9,743

Methylation	Generally of N-terminal phenylalanine, side chain of lysine, arginine, histidine, asparagine or glutamate, and C-terminal cysteine	746	2,846	18,716

Pyrrolidone Carboxylic Acid	N-terminal glutamine which has formed an internal cyclic lactam.	598	584	12,322

Gamma-Carboxyglutamic Acid	Glutamate	371	361	1,924

Farnesylation	Cysteine	61	216	5,349

Myristoylation	Glycine	108	765	10,998

N-Palmitoylation	Cysteine	33	1,279	6,554

S-Palmitoylation	Cysteine	177	2,303	21,287

Geranyl-geranylation	Cysteine	47	819	14,317

S-diacylglycerol cysteine	Cysteine	36	1,529	8,977

GPI anchoring	C-terminal asparagine, asparate, and serine	27	681	-

Deamidation	Amidated asparagine and glutamine (needs to be followed by a G)	38	26	2,022

Sulfation	Serine, threonine, and tyrosine	196	626	15,654

Sumoylation	Lysine	77	259	10,342

Ubiquitylation	Lysine	286	516	8,865

ADP-ribosylation	Arginine	3	203	-

Formylation	Of the N-terminal methionine	28	35	-

Citrullination	Arginine	27	91	-

Nitration	Tyrosine	47	5	1,432

Bromination	Tryptophan	18	3	-

FAD	O-8alpha-FAD tyrosine, Pros-8alpha-FAD histidine, S-8alpha-FAD cysteine, and Tele-8alpha-FAD histidine	12	116	-

S-nitrosylation	Cysteine	9	93	-

Others		1049	2,958	-

Total		45,833	139,909	2,560,047