Major component of the transverse filaments of synaptonemal complexes, formed between homologous chromosomes during meiotic prophase (PubMed:16717126). Required for normal assembly of the central element of the synaptonemal complexes (PubMed:15937223). Required for normal centromere pairing during meiosis (PubMed:22761579). Required for normal meiotic chromosome synapsis during oocyte and spermatocyte development and for normal male and female fertility (PubMed:15937223). Structural component of synaptonemal complexes (PubMed:15937223, PubMed:16717126, PubMed:22761579). Homotetramer that consists of an N-terminal four-helical bundle that bifurcates into two elongated C-terminal dimeric coiled coils. This tetrameric building block potentially self-assembles into a supramolecular zipper-like lattice to mediate meiotic chromosome synapsis. Self-assembly is likely initiated by local proton density at chromosome axis, which is predicted to trigger antiparallel back to back assembly of adjacent C-terminal ends into tetrameric structures that anchor to chromosomal DNA. Then the N-terminal ends are predicted to undergo cooperative antiparallel head to head assembly at the midline of synaptonemal complexes central element to form a zipper-like lattice between properly aligned homologous chromosomes (By similarity). The nascent synapsis generated by SYCP1 is stabilized through interaction with central element proteins SYCE1 and SYCE2 (PubMed:15944401, PubMed:16968740). Forms a complex with EWSR1, PRDM9, SYCP3 and REC8; 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). Interacts with SPO16 (PubMed:30949703). In tripartite segments of synaptonemal complexes, between lateral elements in the nucleus. Its N-terminus is found towards the center of the synaptonemal complex while the C-terminus extends well into the lateral domain of the synaptonemal complex (By similarity). Only rarely detected at centromeres during leptotene and zygotene. Detected at centromeres during mid-diplotene, when it is no longer present along chromosome arms. No longer detected at centromeres at later stages of meiosis (PubMed:22761579). Detected in testis (PubMed:15937223). Detected in spermatocytes (at protein level) (PubMed:22761579). The molecule is in a coiled coil structure that is formed by 4 polypeptide chains. The N-terminal region exhibits a prominent seven-residues periodicity. Mice appear generally healthy, but display complete sterility, due to defective meiosis during germ cell development. Ovaries and testes from mutant mice have strongly reduced weight relative to wild-type. Ovaries display an absence of growing follicles and oocytes. Testes show a complete lack of spermatids and spermatozoa. Synaptonemal complexes from mutant spermatocytes form normal axial elements, but lack the central element; chromosomes do not synapse properly, cross-overs are rare, and DNA repair after meiotic double-strand breaks is impaired.