Table 1.

Summary of PTM databases harbored.

Database	Development Year	Number of PTM Sites Deposited	Database Link	Annotation	Reference
UniProt	2005	Varies according to the keyword search	https://www.uniprot.org	Multiple-type PTM sites for multi-species	[38]
PLMD	2017	284,780	https://plmd.biocuckoo.org/	Protein lysine modification sites for multi-species	[43]
PhosphoSitePlus	2012	598,976	https://www.phosphosite.org/	Multiple-type PTM sites for multi-species	[40]
Phospho.ELM	2010	42,914	https://phospho.elm.eu.org/	Phosphorylation sites for Eukaryotic	[39]
mUbiSida	2014	110,976	https://reprod.njmu.edu.cn/mUbiSiDa	Uniquitination sites mainly for Human and Mouse	[41]
DEPOD	2015	1,215	https://www.depod.org	Dephosphorylation interactions	[42]