Protein-arginine deiminase type-4 (Padi4)

Catalyzes the citrullination/deimination of arginine residues of proteins such as histones, thereby playing a key role in histone code and regulation of stem cell maintenance. Citrullinates histone H1 in'Arg-54' (to form H1R54ci), histone H3 in'Arg-2','Arg-8','Arg-17' or'Arg-26' (to form H3R2ci, H3R8ci, H3R17ci, H3R26ci, respectively) and histone H4 in'Arg-3' (to form H4R3ci).

Acts as a key regulator of stem cell maintenance by mediating citrullination of histone H1: citrullination of'Arg- 54' of histone H1 (H1R54ci) results in H1 displacement from chromatin and international chromatin decondensation, thereby promoting pluripotency and stem cell maintenance. Promotes profound chromatin decondensation during the innate immune response to infection in neutrophils by mediating formation of H1R54ci.