Contributes to histone modification. May position the N-terminus of histone H3 for efficient trimethylation at 'Lys-4' (PubMed:25310983). In neurons and together with DNA N6-methyl adenine demethylase Tet, plays a role in the maintenance of transcriptional activation for specific sets of genes (PubMed:30078725). 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 (PubMed:21694722). Interacts with Set1 (PubMed:21694722, PubMed:21875999, PubMed:22048023). 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 (PubMed:21875999). Component of the Ada2a-containing (ATAC) complex composed of at least Ada2a, Atac1, Hcf, Ada3, Gcn5, Mocs2B, Charac-14, Atac3, Atac2, NC2beta and wds (PubMed:18327268). Interacts with Nup98 (PubMed:25310983). Interacts (via WD repeats) with Tet (via C-terminus) (PubMed:30078725). Expressed in imaginal disks, larval brain, nurse cells, spermatogonia and spermatocytes. Expressed at all stages of development. Larval lethal (PubMed:12471440). Conditional RNAi-mediated knockdown in larval wing imaginal disks results in reduced levels of trimethylated 'Lys-4' in histone H3 (PubMed:25310983). RNAi-mediated knockdown in neurons, does not affect mushroom bodies alpha lobe development (PubMed:30078725). Simultaneous RNAi-mediated knockdown of wds and Tet results in enhanced mushroom body alpha lobe development defects compared to the single Tet knockdown (PubMed:30078725). Belongs to the WD repeat WDR5/wds family.