Inhibits PRC2/EED-EZH1 and PRC2/EED-EZH2 complex function by inhibiting EZH1/EZH2 methyltransferase activity, thereby causing down-regulation of histone H3 trimethylation at 'Lys-27' (H3K27me3) (PubMed:31086175). Probably inhibits methyltransferase activity by limiting the stimulatory effect of cofactors such as AEBP2 and JARID2 (By similarity). Inhibits H3K27me3 deposition during spermatogenesis and oogenesis (PubMed:31451685). Interacts with PRC2/EED-EZH1 complex member EZH1 and with PRC2/EED-EZH2 complex member EZH2; the interaction blocks EZH1/EZH2 methyltransferase activity (PubMed:31086175). Interacts (via C-terminus) with SUZ12 which is a member of the PRC2/EED-EZH1 and PRC2/EED-EZH2 complexes (By similarity). Highly expressed in ovary with lower expression in testis and very low levels in other tissues tested including prostate, brain, kidney, spleen and liver (PubMed:31451685). During spermatogenesis, expressed mainly in spermatogonia with very low expression in spermatocytes I and II (PubMed:31451685). No overt developmental defects with mutant adults appearing indistinguishable from wild-type (PubMed:31451685). Two-fold increase in H3K27me2 and H3K27me3 levels in germ cells in testis but males display normal testis-to-body weight ratio and normal fertility (PubMed:31451685). Increased H3K27me3 levels in postnatal oocytes and slight increase in the number of oocytes with lagging chromosomes (PubMed:31451685). No significant differences in the number of primordial, primary and secondary/antral follicles of pre-pubertal females but older females show a reduced number of follicles at 16 weeks (PubMed:31451685). Females have smaller ovaries and give rise to fewer progeny as they age (PubMed:31451685).