Chromatin reader that specifically recognizes and binds histone H3 both trimethylated at 'Lys-4' and asymmetrically dimethylated at 'Arg-8' (H3K4me3 and H3R8me2a) and acts as an activator of Wnt signaling pathway downstream of PRMT2. In case of cancer, promotes cell cancer proliferation via activation of the Wnt signaling pathway (By similarity). Overexpression induces metaphase arrest and chromosomal instability (PubMed:18543248). Localizes to active rDNA loci and promotes the expression of rRNA genes. May play a role in cell-cycle regulation during the transition from gamete to embryo. Involved in oocyte meiotic resumption, a process that takes place before ovulation to resume meiosis of oocytes blocked in prophase I: may act by regulating maternal transcripts to control meiotic resumption (PubMed:23894536). Homodimer; may form higher-order oligomers. Interacts with TCF7L2/TCF4; the interaction is direct (By similarity). Interacts with HABP4 and SERBP1 (PubMed:23894536). Interacts with C11orf84/SPINDOC (By similarity). Associates with the meiotic spindle. Oocyte, egg, and very early embryo; not in the 8-, and 16-cell stage of the embryo. Isoform 1: Present in testis. Isoform 1 is more highly expressed in adult testes compared with newborn testes (at protein level). Gametogenesis. Synthesized from maternal transcripts but not from the zygote genome. The 3 tudor-like domains (also named Spin/Ssty repeats) specifically recognize and bind methylated histones. H3K4me3 and H3R8me2a are recognized by tudor-like domains 2 and 1, respectively. Phosphorylated during oocyte meiotic maturation. Post-translationally modified during the first mitotic cell cycle. Early postnatal lethality. Ovarian folliculogenesis and oocyte growth appear normal but fully grown oocytes show defects in resuming meiosis. Belongs to the SPIN/STSY family.