Dioxygenase that can both act as a histone arginine demethylase and a lysyl-hydroxylase. Binds 1 Fe(2+) ion per subunit. Belongs to the JMJD6 family. Was initially thought to constitute the phosphatidylserine receptor, a receptor that mediates recognition of phosphatidylserine, a specific marker only present at the surface of apoptotic cells, and participates in apoptotic cell phagocytosis. However, its nuclear localization and the fact that it is not involved in phagocytosis during apoptosis strongly suggest that it does not constitute the receptor for phosphatidylserine and is not involved in apoptotic cell removal.