Component of the synaptonemal complexes (SCS), formed between homologous chromosomes during meiotic prophase (PubMed:11311943, PubMed:22761579). Required for centromere pairing during meiosis in male germ cells (PubMed:22761579). Required for normal meiosis during spermatogenesis and male fertility (PubMed:10678170). Plays a lesser role in female fertility (PubMed:10678170, PubMed:12004129). Required for efficient phosphorylation of HORMAD1 and HORMAD2 (PubMed:22346761). Component of the lateral elements of synaptonemal complexes (PubMed:16717126). Homotetramer; the tetrameric helix bundles assemble end to end into long homopolimeric fibers that exhibit a transversal striation with a periodicity of about 20 nm (in vitro) (By similarity). Interacts with SYCP2 (PubMed:16717126). Forms a complex with EWSR1, PRDM9, REC8 and SYCP1; complex formation is dependent of phosphorylated form of REC8 and requires PRDM9 bound to hotspot DNA; EWSR1 joins PRDM9 with the chromosomal axis through REC8 (PubMed:27932493). It is present in early unpaired cores, in the lateral domains of the synaptonemal complex and in the chromosome cores when they separate at diplotene. It is found axial to the metaphase I chromosomes and in association with pairs of sister centromeres. The centromere-associated protein becomes dissociated from the centromeres at anaphase II and is not found in mitotic metaphase centromeres (By similarity). The phosphorylated form localizes preferentially to unsynapsed chromosomal regions (PubMed:22346761). Detected in oocytes (PubMed:16717126). Detected in spermatocytes and testis (at protein level) (PubMed:10678170, PubMed:16717126, PubMed:22761579). Composed of a long central coiled coil domain. The N-terminal and C-terminal regions interact with DNA. Phosphorylated. Homozygous males with null mutations have smaller testes and are sterile, due to massive apoptotic cell death of male germ cells during meiotic prophase. Spermatocytes fail to form axial/lateral elements and synaptonemal complexes, and the chromosomes in the mutant spermatocytes do not synapse (PubMed:10678170). In contrast, females are fertile and generate healthy offspring. However, they exhibit a sharp reduction in litter size that increases with advancing maternal age (PubMed:10678170, PubMed:12004129). In contrast to wild-type, a high percentage of the mutant embryos display aneuploidy (PubMed:12004129). Belongs to the XLR/SYCP3 family.