Interacts with PAXIP1/PTIP; the interaction is direct and is required for the association with the rest of the PTIP complex. Component of the MLL3/MLL4 complex at least composed of MLL3, MLL4, ASH2L, RBBP5, DPY30, WDR5, NCOA6, KDM6A, PAXIP1/PTIP and C16orf53/PA1.