All characterized lysine demethylases other than KDM1A belong to the jumonjiC domain (JmjC) containing family.The JmjC KDMs are members of the Cupin superfamily of mononuclear Fe (II) dependent oxygenases, which are characterized by the presence of a double-stranded beta-helix core fold. The JmjC KDMs require 2 oxoglutarate (2 OG) and molecular oxygen as co substrates, producing, along with formaldehyde, succinate and carbon dioxide. This hydroxylation based mechanism does not require a protonatable lysine e amine group and consequently JmjC containing demethylases are able to demethylate tri , di and monomethylated lysines.
KDM4A-D (JMJD2A-D/JHDM3A-D) catalyse the demethylation of di- or tri-methylated histone H3 at lysine-10 (H3K9Me2/3) (Cloos et al. 2006, Fodor et al. 2006, Whetstine et al. 2007), with a strong preference for Me3 (Whetstine et al. 2007). MINA, a bifunctional histone lysine demethylase and ribosomal histidine hydroxylase, demethylates trimethylated lysine-10 of histone H3 (Lu et al. 2009).
KDM4A (JHDM3A) can also demethylate lysine-37 of histone H3 (H3K36Me2/3) (Klose et al. 2006).