The peptidylarginine deiminases expressed in human epidermis differ in their substrate specificities and subcellular locations.

Deimination, a post-translational modification catalyzed by peptidylarginine deiminases (PADs), appears as a crucial Ca(2+)-dependent event in the last steps of epidermal differentiation. In normal human epidermis, where the deiminated proteins are filaggrin and keratins, PAD1, 2 and 3 are expressed but their relative role is unknown. The three PADs, produced as active recombinant forms, showed distinct synthetic-substrate specificities, various efficiencies to deiminate filaggrin and particular calcium and pH sensitivities.