Protein Arginine Deiminases (PADs) are guanidino-modifying enzymes belonging to the amidinotransferase superfamily and are designated PAD1-4 and PAD6. PADs are calcium-dependent enzymes that catalyze the post-translational modification of target proteins by converting arginine to citrulline. The various PADs exhibit tissue specific expression and different subcellular localization. PAD1 is expressed in uterus and throughout the epidermis. PAD1 and PAD3 are speculated to mediate deimination of epidermal filaggrin (filament aggregation protein) and keratins, proteins involved in maintaining skin hydration.
