Component of the SET1 complex that specifically di- and trimethylates 'Lys-4' of histone H3 and of the MLL3/4 complex which also methylates histone H3 'Lys-4'. Core component of several methyltransferase-containing complexes. Component of the SET1 complex, composed at least of the catalytic subunit Set1, wds/WDR5, Wdr82, Rbbp5, ash2, Cfp1/CXXC1, hcf and Dpy-30L1. Component of the MLL3/4 complex composed at least of the catalytic subunit trr, ash2, Rbbp5, Dpy-30L1, wds, hcf, ptip, Pa1, Utx, Lpt and Ncoa6.