Major component of the transverse central element of synaptonemal complexes (SCS), formed between homologous chromosomes during meiotic prophase. Required for chromosome loading of the central element-specific SCS proteins, and for initiating synapsis between homologous chromosomes. Chromosome loading appears to require SYCP1. Required for fertility. Homodimer. Interacts with SYCE1. Interacts with SYCE2. Interacts with proteasome subunit PSMA8; to participate in meiosis progression during spermatogenesis (By similarity). Interacts with SPO16 (By similarity). Colocalizes with SYCE1 in the central elements.