The EZH2 (Y641F) TR-FRET Assay Kit is designed to measure activity of the mutant EZH2 complex (EZH2 (Y641F)/EED/SUZ12/RbAp48/ AEBP) in a homogeneous 384 reaction format. This FRET-based assay requires no timeconsuming washing steps, making it especially suitable for high throughput screening applications. The EZH2 (Y641F) TR-FRET Assay Kit comes in a convenient format, with histone H3 peptide substrate, a Tb-labeled antibody against methylated K27 residue of Histone H3, S-adenosylmethionine, methyltransferase assay buffer, TR-FRET detection buffer, dye-labeled acceptor, and purified EZH2 (Y641F) complex for 384 enzyme reactions. The key to the EZH2 (Y641F) Assay Kit is a highly specific antibody that recognizes methylated Histone H3K27. With this kit, only three simple steps on a microtiter plate are required for methyltransferase detection. First, S-adenosylmethionine is incubated with a sample containing assay buffer and methyltransferase enzyme for 240 minutes. Next, antibody is added. Finally, dye-labeled acceptor is added followed by fluorescence reading.