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 epsilon-amine group and consequently JmjC containing demethylases are able to catalyse demethylateion of tri , di and monomethylated lysines. KDM3A (JHDM2A), KDM3B (JHDM2B), KDM7A (JHDM1D), PHF8 (JHDM1E) and PHF2 when complexed with ARID5B (Wen et al. 2010, Baba et al. 2011) are specific for mono or di-methylated lysine-10 on histone H3 (H3K9Me1/2) (Yamane et al. 2006, Kim et al. 2012, Horton et al. 2010, Huang et al. 2010, Loenarz et al. 2008, Feng et al. 2010, Fortschegger et al. 2010, Qi et al. 2010).