Figure 4. Histone arginine demethylation.
(A) PAD4 can convert methylated or unmethylated arginine to citrulline. The reaction then blocks arginine methylation from occurring on histone tails. (B) JMJD6 is an Fe(II)- and 2-oxoglutarate (α-KG)-dependent dioxygenase which removes methyl groups from symmetrical dimethyl H4R3 (SDMA) or asymmetrical dimethyl H4R3 (ADMA) to generate monomethylarginine (H4R3me1).