Transcriptional activator that exhibits a unique DNA binding specificity for CpG motifs; enriched at promoters containing the trimethylation mark on histone H3 'Lys-4' (H3K4me3) (PubMed:24653213). Forms part of the SET2 complex and interacts with the SIN3S HDAC complex at promoters (PubMed:31602465). Required for H3K4 trimethylation and plays a repressive role in the expression of heat shock and salt-inducible genes (PubMed:30941832). Required for fertility, in cooperation with class I histone deacetylases (HDACs) (PubMed:24653213, PubMed:30941832, PubMed:31602465). Component of the SET2 complex (also known as the SET1/COMPASS complex), which contains at least set-2, swd-2.1, cfp-1, rbbp-5, wdr-5.1, dpy-30 and ash-2 (PubMed:31602465). Within the complex, interacts with wdr-5.1, ash-2 and dpy-30 (PubMed:31602465). Also interacts with the SIN3S complex, which contains at least sin-3, hda-1, athp-1 and mrg-1 (PubMed:31602465). Interacts with sin-3, hda-1 and mrg-1 (PubMed:31602465).