Mutation of Tyr245 or Tyr305 in SET7/9 (Determine 4b ) alters its specificity from an H3 K4 mono-methylase to a tri- and di-methylase, respectively 16 , 21 , whereas an Phe281Tyr mutation within the lysine-binding pocket of DIM-5 (Determine 4c ) converts this protein to an H3 K9 mono- or di-methylase sixteen These mutations exemplify the F/Y swap (Determine 1 ) that establishes SET-domain product specificities.

For example