Wdr5 belongs to the family of WD repeat proteins which are involved in different cellular processes such as cell cycle progression, signal transduction, apoptosis, and gene regulation. It is a component of the Set1A and Set1B histone H3 methylation complexes. These complexes methylate lysine 4 of H3, thereby activating gene transcription. Wdr5 interacts with H3 dimethyl K4, but not with tri or mono methylated H3K4.