Protein-arginine deiminase (IPR004303)

Short name: PAD

Overlapping homologous superfamilies


Family relationships



In the presence of calcium ions, Protein-arginine deiminase (PAD) enzymes EC: catalyse the post-translational modification reaction responsible for the formation of citrulline residues from protein-bound arginine residues [PMID: 10092850]. Four PAD isotypes of PAD have been identified in mammals, a fifth may also exist. Non-mammalian vertebrates appear to have only a single PAD enzyme. All known natural substrates of PAD are proteins known to have an important structural function, such as keratin (PAD1), intermediate filaments or proteins associated with intermediate filaments. Citrulination may have consequences for the structural integrity and interactions of these proteins. Physiological levels of calcium appear to be too low to activate these enzymes suggesting a role between PAD activation and loss of calcium homeostasis during terminal differentiation and cell death (apoptosis).

GO terms

Biological Process

GO:0018101 protein citrullination

Molecular Function

GO:0004668 protein-arginine deiminase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.