Members of this family are found in mammals. In the presence of calcium ions, PAD enzymes EC:3.5.3.15 catalyse the post-translational modification reaction responsible for the formation of citrulline residues: Protein L-arginine + H2O <=> Protein L-citrulline + NH3. Several types are recognised (and included in the family) on the basis of molecular mass, substrate specificity, and tissue localisation. The expression of type I PAD is known to be under the control of oestrogen [3].

1: Peptidylarginine deiminase of the hair follicle: characterization, localization, and function in keratinizing tissues. Rogers G, Winter B, McLaughlan C, Powell B, Nesci T; J Invest Dermatol 1997;108:700-707. PMID:9129218

2: Protein deimination in the rat brain after kainate administration: citrulline-containing proteins as a novel marker of neurodegeneration. Asaga H, Ishigami A; Neurosci Lett 2001;299:5-8. PMID:11166924

3: Molecular cloning of cDNAs of mouse peptidylarginine deiminase type I, type III and type IV, and the expression pattern of type I in mouse. Rus'd AA, Ikejiri Y, Ono H, Yonekawa T, Shiraiwa M, Kawada A, Takahara H; Eur J Biochem 1999;259:660-669. PMID:10092850