Protein involved in the remodeling of chromatin thereby regulating various processes including transcription, chromosome synapsis and genome integrity (PubMed:22172672, PubMed:22212480, PubMed:17215300, PubMed:30929290). Mainly binds genomic loci carrying trimethylated histone H3 'Lys-36' (H3K36me3) or 'Lys-4' (H3K4me3), and acetylated histone H3 'Lys-9' (H3K9ac), 'Lys-27' (H3K27ac) (PubMed:30425042, PubMed:31118512). During meiosis, required for the presynaptic pairing of homologous chromosomal regions outside of the pairing center and for the progression of chromosome synapsis (PubMed:22172672, PubMed:22212480). Essential maternal factor required in postembryonic germline development and in maintaining germ cell identity (PubMed:12175490, PubMed:30425042). Plays an important role in maintaining genomic integrity in primordial germ cells (PGCs) during meiosis by regulating DNA double-strand break (DSB) repair and synapsis (PubMed:22212480, PubMed:30929290). Also, required for chromatin-based transcriptional silencing in PGCs and for silencing of X-linked genes in the maternal germ line (PubMed:17215300, PubMed:30929290). By retaining histone acetyltransferase, cbp-1, in euchromatin, promotes the anchoring of heterochromatin at the inner nuclear membrane in intestinal and hypodermal cells (PubMed:31118512). Component of the SIN3S complex, which contains at least sin-3, hda-1, athp-1 and mrg-1 (PubMed:31602465). Interacts with cfp-1, a component of the SET2 complex (PubMed:31602465). Interacts with rfp-1 (PubMed:25564623). Concentrated on euchromatic regions marked by H3K36me2/me3 and probably enriched on autosomes. Expressed in oocytes (at protein level) (PubMed:12175490). Expressed mainly in germ cells, but also at lower levels in several somatic cell types, including intestinal cells (PubMed:17215300). Expressed in embryos, L1 larvae and adult hermaphrodites and decreases drastically between the L2 and L4 larval stages (at protein level) (PubMed:12175490, PubMed:17215300). In late embryos and young larvae, expressed at higher levels in the two primordial germ cells (PGCs), Z2 and Z3, than in somatic blastomeres (PubMed:17215300, PubMed:30929290). Expressed at a relatively constant level throughout the distal end of the gonad at the L1 stage, with no decrease as cells enter into meiotic prophase (PubMed:25564623). Maternal-effect lethality and sterility (PubMed:17215300). Primordial germ cells (PGCs) do not proliferate normally and death of germ cells may be as a result of necrosis or increased apoptosis (PubMed:17215300, PubMed:22212480). Increased proportion of oocytes with fragmented chromosomes as a result of irradiation (PubMed:22212480). Tumorous germline phenotype that is suppressed on a rfp-1;glp-1 double mutant background (PubMed:25564623). Germline progression from leptotene/zygotene to pachytene is defective (PubMed:22212480). Perinuclear anchoring of heterochromatin in intestinal or hypodermal cells is disrupted and exacerbated on a cec-4 mutant background, but is partially blocked by RNAi-mediated knockdown of cbp-1 or atf-8 (PubMed:31118512). RNAi-mediated knockdown causes defective homologous chromosome pairing, complete absence of the germline in almost all adult F1 progeny and slight underdevelopment of the somatic gonad (PubMed:12175490, PubMed:22172672). RNAi-mediated knockdown strongly blocks mitosis of PGCs at early larval stages, and the arrested PGCs may degenerate during late larval stages (PubMed:12175490). RNAi-mediated knockdown induces germ cells to undergo conversion into neuron-like cells (PubMed:30425042). RNAi-mediated knockdown causes a slight increase in levels of the constitutive heterochromatin mark, trimethylated histone H3 'Lys-9' (H3K9me3), and an increase of acetylated histone H3 'Lys-14' (H3K14ac) (PubMed:30425042). Simultaneous RNAi-mediated knockdown of mep-1 suppresses the ectopic expression of pgl-1 protein and the overexpression of pgl-1 mRNA in larvae (PubMed:17215300). RNAi-mediated knockdown induces germ cell apoptosis; however, on clk-2 or cep-1 mutant backgrounds apoptosis is reduced substantially (PubMed:22212480).