The MLL3 Complex Chemiluminescent Assay Kit is designed to measure MLL3 activity for screening and profiling applications, using purified MLL3 and its complex components: WDR5, RbBP5, Ash2, and DPY30. The key to the MLL3 Complex Chemiluminescent Assay Kit is a highly specific antibody that recognizes methylated K4 residue of Histone H3. 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. Next, primary antibody is added. Finally, the plates are treated with an HRP-labeled secondary antibody followed by the addition of the HRP substrate to produce chemiluminescence that can be measured using a chemiluminescence reader.